One more question. If you can get the car started, and drive it for at least half an hour, then shut it down for 5 minutes, will it start right up? In other words, is the problem that the car won’t start well when cold, but will start easily when warmed up, or is the problem that is always starts poorly even when warmed up.
(If you don’t know, it would be good to test this. Drive long enough that you can get hot air out of the heater, and take it on the highway if possible. This information may help the next mechanic to diagnose the problem. It almost sounds like your problem could be described as “my car starts then stalls right away” instead of “my car won’t start.”)
I have had two episodes where I had driven from place to place with probably 30+ minutes inbetween places where the car wouldn’t start at the second stop and had to be towed. I have not driven on the highway because I haven’t needed to go that way. I do know the majority of the time it has NOT started has been either after it sat in the garage for a couple of hours (running errands in the morning and then it didn’t start in the late afternoon) or it sat overnight and didn’t start in the morning. The dealer did ask me these questions too and so they tried the “cold start” and then off and an during the day when they had it the week before so at least they looked at that which makes me feel better. I don’t know if they drove it on the highway or not though. Most of the time it just wouldn’t start as opposed to stalling out. The tow truck guys always tried to start it as well just to make sure and they couldn’t get it to start either. The stalling out part has been new since the replacement parts were installed which doesn’t help you does it.
Maybe somebody else here will have a more definite explanation will all this additional info.
If it will sometimes start and keep running if you have your foot on the gas, this suggests a particular sub-family of problems from the “won’t start” universe of possibilities. It seems more likely to be a fuel or air problem than a spark problem. Unfortunately, there are still a lot of possibilities. (The air intake control valve was not an unreasonable attempt, although I think the crank angle sensor and cam sensor were probably on the wrong track.) You should definitely explain these various experiences to the next mechanic.
I would still do the fuel pump relay because it’s only 10 bucks and you can do it yourself. And I would ask the next mechanic to install a fuel pressure gauge and leave it in where you can see it, just because that would make it real easy to tell if it was a fuel problem if the starting problems keep occurring.
I’ll stop monopolizing the discussion now and let actual smart people take a crack at it. 
Thank you again for taking so much time for the information and suggestions. I will mention the fuel pump relay. I’m sure this is just one of those problems that really is going to be a “hit and miss” issue with an older car. I certainly understand the mechanics are doing what they think will work and I am giving them as much information as possible to help diagnose the problem being a female and not knowing what any of these parts do. All I can tell them is when the car won’t start and the 2-month long saga of what has been tried with a copy of all the repair bills as documentation for their review. Thank you again for all your help.
This might seem like a stupid question, but do you have another factory key for the car, and if so, did you try it? This car has an engine immobilizer that enables the ignition and fuel injectors - thereby allowing the car to start - only if it “recognizes” the transponder code, which is a chip built into the key. I believe - but don’t remember for certain - the “security” light will flash rapidly if there is such a malfunction.
We had the ignition replaced and therefore we were given another key. The original key only works the locks now and the new ignition key starts the car. I can try the second one and see if it will work. The car is back at the dealer now for the 3rd time so I’ll have to try it if it makes it home. I haven’t noticed the security light flashing though and the dealer tech said a code would have indicated a security problem but that hasn’t shown up at this point. Thank you!
I didn’t see the earlier comment about the exhaust smoke with a gasoline odor. Does it do this every time it fails to start?
No, that just started today. The first time was early this morning when I was trying to start it at which time I immediately turned it off. The second time was this afternoon at 2:30 as I was trying to start it to take it back to the dealer. The dealer tech said it may just be excess fuel burning off. I am now convinced the car is “possessed”.
First, find a Master Certified Mechanic.Preferably with over 20 years of experience.
Did you post that the starter motor works fine,but the engine won’t start? At this point I would suspect the ignition switch . It is possible this vehicle has an oil pressure switch that controls the fuel pump operation.
This vehicle has to have some stored codes in the computer. If not I would suspect the computer or Ignition/fuel pump relay.
A wiring issue such as an exposed wire or bad ground. You need to find a better mechanic.
Check Nissan TSB {technical service bulletin} NTB97-057, classification EC97-026. This deals with intermitent Maxima no start condition.
Thank you for the information. It is at the Nissan dealer for the 3rd time now but I’ll pass this bulletin on to them. It’s a '96 Maxima and the ignition has been replaced and they have said for the 3rd time, the fuel pump is okay but I haven’t heard anything about an oil pressure switch. The 2nd mechanic that I went to said the computer had been “cleared” so no codes were showing up. I have no idea who would “clear” a car computer because it has only been in for oil changes and routine stuff until now. Thanks for your advice. I’ll pass it on.
I hope the service personel are mature enough to accept input from other technicians. Tell them the advice was passed on to you by a Master Certified Mechanic with 36 yrs experience.
Fixing the problem for a customer is the important aspect.Pride should not be an issue here. Good luck!
The techs all look to be in their 20’s or early thirties! They have been very kind though. I can always tell them you are my cousin because everyone from the south is related somehow!
Thank you again for taking the time to write. Wish your expertise had been here 2 months ago!