Intermittent heat and burning antifreeze

Sorry this is a long one. Can anyone help me figure out what is wrong here? I drive a 94 Ford Ranger with about 235,000 miles on her. I just moved half way across the country away from my normal mechanics (Dad and brother). I needed new breaks so I went to a local mechanic in town. My power steering had recently gotten a very slow leak so I asked if they could look at that too. The mechanic said the hose broke as soon as he touched it, so I had him replace it. I also brought up that my truck had started to run hot (but had never overheated) when it sat still idling this summer. Also, in the winter while it was idling the heat wouldn’t work unless I revved the engine, and during the summer the a/c didn’t work while it was idling, but both worked great while she was moving. I had discussed with my dad previously that the water pump was probably on it’s last leg so when he told me I needed a new one I told him to replace it. He also told me that I needed a new thermostat so I signed up for that too. After I got it back I have had heat intermittently and there doesn’t seem to be any reason why I sometimes have heat and sometimes don’t (mostly didn’t). He told me to check the coolant levels which I did and it was all full and fine, but still no real heat. Then a few days later I started my truck to warm it up before going out and after awhile I went back into the garage I found power steering fluid all over the place. I turned off my truck and called the mechanic again to let him know the hose had blown. He told me it couldn’t be the brand new hose, but when I took it in he found out that it was, so he re-crimped it, and found the thermostat he had put on was bad so he replaced it. Now since I’ve gotten it back I smell burning antifreeze for a minute or two after starting my truck, but then it goes away, and I still have intermittent heat, although it’s better than it was. I’ve checked the oil and antifreeze and it doesn’t look like they have mixed at all and the levels are fine so I’m assuming the head is ok. The only leak I can find is the hose connection out of the coolant overflow/holding tank, and I don’t see any puddles on my garage floor. The mechanic is insisting that I need a new heater core, and claims that it is plugged up and that is what is causing the burning antifreeze and heat issues, but my dad just replaced it two years ago (along with my brother replacing the radiator). I did not smell burning coolant until the last time I brought it in when he replaced the thermostat for the second time and re-crimped the hose on the power steering. And in my thinking if it was the heater core being blocked I’d never have heat instead of sometimes having heat and sometimes not. I didn’t have intermittent heat issues before all this started (except when idling), and now everything on my heating system is new (within two years). My dad says there is no way it’s the heater core, but he can’t tell what’s wrong over the phone. Any ideas here? I’m thinking of going to a new mechanic.

Pass no paragraph spacing.

 So you don't know what is wrong or do you really do need it in paragraph form to figure it out?

Sorry this is a long one. Can anyone help me figure out what is wrong here?
I drive a 94 Ford Ranger with about 235,000 miles on her. I just moved half way across the country away from my normal mechanics (Dad and brother). I needed new breaks so I went to a local mechanic in town. My power steering had recently gotten a very slow leak so I asked if they could look at that too. The mechanic said the hose broke as soon as he touched it, so I had him replace it.
While I was there I brought up that my truck had started to run hot (but had never overheated) when it sat still idling this summer. Also, in the winter while it was idling the heat wouldn’t work unless I revved the engine, and during the summer the a/c didn’t work while it was idling, but both worked great while she was moving. I had discussed with my dad previously that the water pump was probably on it’s last leg so when he told me I needed a new one I told him to replace it. He also told me that I needed a new thermostat so I signed up for that too.
After I got it back I have had heat intermittently and there didn’t seem to be any reason why I sometimes had heat and sometimes didn’t (mostly didn’t). He told me to check the coolant levels which I did and it was all full and fine, but still no real heat.
A few days later I started my truck to warm it up before going out and after awhile I went back into the garage I found power steering fluid all over the place. I turned off my truck and called the mechanic again to let him know the hose had blown. He told me it couldn’t be the brand new hose, but when I took it in he found out that it was, so he re-crimped it, and found the thermostat he had put on was bad so he replaced it.
Now since I’ve gotten it back I smell burning antifreeze for a minute or two after starting my truck, but then it goes away, and I still have intermittent heat, although it’s better than it was. I’ve checked the oil and antifreeze and it doesn’t look like they have mixed at all and the levels are fine so I’m assuming the head is ok. The only leak I can find is the hose connection out of the coolant overflow/holding tank, and I don’t see any puddles on my garage floor.
The mechanic is insisting that I need a new heater core, and claims that it is plugged up and that is what is causing the burning antifreeze and heat issues, but my dad just replaced it two years ago (along with my brother replacing the radiator). I did not smell burning coolant until the last time I brought it in when he replaced the thermostat for the second time and re-crimped the hose on the power steering.
My thinking is if it was the heater core being blocked I’d never have heat instead of sometimes having heat and sometimes not. I didn’t have intermittent heat issues before all this started (except when idling), and now everything on my heating system is new (within two years). My dad says there is no way it’s the heater core, but he can’t tell what’s wrong over the phone.
Any ideas here? I’m thinking of going to a new mechanic.
Did that make it easier to figure out?

What oldschool is saying is that attempting to figure out what’s wrong with a vehicle can be difficult even with the vehicle in hand.
Trying to figure it out based on a thesis over the internet makes it doubly hard.

The wheat needs to be separated from the chaff so to speak and with all of the extras combined with no paragraph spacing kind of makes the vision blurry.
I’m on the way out so I might try to weed through this later and post something.

Seriously, it would help if you just use clipped sentences and stick strictly to the symptoms. It take so long to read through it that by the time one is at the halfway point the first part is forgotten.

I was thinking more info was better but OK the short version is…

I have intermittent heat and can smell the coolant burning for the first 1-2 minutes of driving my 94 ford ranger. The mechanic who has recently been working on it insists the problem is because my heater core is blocked.

My heater core is only 2 years old and now everything on my heating system has been replaced. I didn’t have intermittent heat until he replaced the water pump, and original thermostat.

I didn’t have burning antifreeze smells until he replaced the thermostat for the second time because the first one was defective. I’ve checked and didn’t find a leak there, just one coming from the hose of the reservoir tank.

I had wonderful heat before he started replacing stuff. I don’t have any ideas besides he put in another bad thermostat, but what are the odds?