If I follow your thread… the P0101 causes are:
- Faulty mass air flow sensor
- Intake air leaks
- Dirty mass air flow sensor
- Dirty mass air filter
- Mass air flow sensor harness is open or shorted
- Mass air flow sensor circuit poor electrical connection
Logically replacing the MAF seems like a smart thing to do although notice the 5th and 6th possible causes. That is important… wiring problems. Since you don’t know and can’t tell us the codes mechanic #2 saw that indicated the need to replace the throttle body I’d guess a P0123 and maybe the P2135 so hardware was replaced BUT damaged wiring COULD be the cause as the mechanic suspected when his part did not fix the problem.
The wiring shop suggested a clog in the cat… stupid diagnosis from a shop that should know better… A wiring fault… a short to ground especially… can occur when driving causes vibration and engine movement stressing the wiring. That means it is intermittent and hard to find. The wiring shop did not find it, doesn’t mean there isn’t a problem.
So now you bought a scan tool and are finding a ton of codes. All of those codes have wiring issues as one of their likely causes. That is a BIG hint. At least it is to me and should be to any mechanic reviewing your post and list of codes.
This is a difficult problem to find and fix so I’d suggest it is beyond your skills to do it alone. I’d look far and wide in your area for the best diagnostic shop in the area. The kind of shop that other shops refer to when they can’t fix things. Ask friends, search google, YP, even ask shops themselves. Research is your friend as is information.
Share what you’ve posted here with the best shop you can find and get their opinion. Be ready to pay for their diagnostic time; you want to KNOW what is wrong, not just throw parts at the problem. (You see how that has not worked!) Better to spend $350 on diagnostic time and get it fixed than toss another $900 worth of parts at it and still have the problem. Good Luck.