I dont know where else to turn my 89 trans am tpi has been driving me nuts it has been running way too rich to the point it doesn't want to start after driving it about 10 min, sometimes I have to wait a whole day for it to start again. I replaced the fuel injectors o2 sensor, throttle positioning sensor intake air temp sensor and water temp sensor and it is still doing the same thing so my head is up against the wall I have never had a problem with a car before that seemed impossible to fix the only thing that I have not replaced is the mass air flow and I dont want to pay 300 for something that may not fix the problem. and the check engine light has only come on twice for like 2 min in the 2 years that I have owned the car. any help would be greatly appreciated because I have no idea what else it could be other than the ecu

 

Have you tested the fuel pressure? When you turn off the key, does it hold pressure or does it leak down quickly?
If it leaks down you have a mechanical leak, not a sensor problem.

The conditions that trigger check engine codes are pretty simplistic on OBD-1. I don't know if the MAF should be your primary suspect, but the lack of a code doesn't rule it out at all.

However, if it's running consistently rich then I would think you'd have to get a rich exhaust code. Assuming it reaches closed loop mode then the O2 sensor will report rich, the ECM will try to compensate, and if it still stays rich then before long a code would pop up. So I'm confused how you're not getting at least a rich exhaust code. Is it warming up properly and getting into closed loop? Are you sure the light works reliably (it should turn on during the bulb test)?
Do you have an aftermarket chip installed? Are you sure that it's rich, and not a different problem?