My son has a 92 skylark with 3.3 motor, SES light is on with codes:
16 system voltage high or low,
22 throttle position sensor voltage low
43 electronic spark control circuit.
Engine usually idles at 3000 rpm, sometimes it will idle fine and SES light goes out. At one point the exaust manifolds glowed orange and temp guage was almost in the red, but engine temp is fine now.
I read on a post here that its the TPS sensor. Replacing the sensor didnt help anything. Ive thought maybe a bad connection on a wire and tugged and shook the harnesses when motors was idleing fine but it didnt change anything, shifting from P to D or D to R to shake the harnesses doesnt help either. I really hate to just throw a bunch of parts at this car.
Why would the symptom come and go as it does?

Any ideas on this problem are appreciated?

you have a vacuum leak somewhere, causing the engine to lean out and get hot.

I looked for vacume leaks but then, why would it quit having a problem at times.
A couple days ago I took it to the dealer. They said the car has a faulty temp sensor, a faulty electronic spark control unit and the TPS I had installed needs to be programed. They did the work and so far its running fine.