Need help Tried everything 1993 sedan deville owner
 

My car runs great for the first ten to fifteen minutes after starting after that it runs like crap , it misses, backfires , and dies all the time. I've replaced all sensors new plugs and plug wires , new distributor , repaired all bare wires, I've checked everything repair manual said to check and it still only runs good for the first 15 minutes. Can anyone tell me what the problem cold be because I'm ready to buy a PCM and PROM out of a car at a wrecking yard , same year and model and if I do can I just remove from one car and install into my car or does it have to be programmed first?

Do you has FSM? Codes? Distributor has to installed with the correct orientation be cause it has cam sensor. It is wrong injectors will pray at wrong time. Ground wires clean on not painted bolts/studs. Check egr make sure valve isn't open.

Have you replaced the O2 sensors?
WHAT THE HOME MECHANIC NEEDS TO KNOW ABOUT O2 SENSORS