1992 Oldsmobile Toronado Idling

Engine Performance problem
1992 Oldsmobile Toronado 6 cyl Front Wheel Drive Automatic

I have a 92 Olds Toronado Trofeo 3.6 VB with no turbo charge. My car has no trouble codes BUT WILL NOT IDLE. When I first start engine, I can hold petal to a steady 15,000 rpm for a long time. When I start 2nd time I can't hold to 15,000 rmp. It will roar to 40 and 60,000 rpm with a push of the gas pedal and it sounds like the exhaust is spitting. I have a factory shop manual for my car. And I followed all the procedures and diagnostics in the manual. Everything checks ok. Fuel pressure 40 PSI, noid lights show all injectors firing and all spark plugs fire. I removed & cleaned fuel injectors. Following the codes and procedures I have installed the following: crankshaft position sensor, camshaft position sensor, coolant temp sensor, IAC, fuel press regulator, fuel pump relay and fuel filter. After installing three of these items, a day at a time. The car started and idled great, even took it on test runs. But the next day I was back to square one. (Would not idle)! The three parts that seem to help were: 1. Crankshaft position, sensor 2. Fuel pump relay and 3. Coolant temp sensor.