740 Gl, 164M miles, runs great on the road, no hesitaion, misfires or studders, only smooth sailing and full responsiveness. At idle, runs like crap in gear, a little better in Park or Nuetral. It idles poorly and will eventual die. Hard to restart. Second time I crank, it will start but is just as rough.
When I bought the car 3 months ago it had just been dealer serviced. New plugs, wires, cap and throttle body service. Here's what I've done: replaced MAF sensor, air idle control valve, flame trap, fuel filter, fuel pressure regulator, ECT sensor and replaced all orings on fuel injectors. I've checked for vacuum leaks (found none) rechecked spark (fine) both fuel pumps are running. When I replaced the ECT sensor, I pulled the manifold and replaced the gasket. I jumped and bypassed the TPS (no difference)
Oh yah, NO CODES.
I'm fried here, can't think of anything else. Someone suggested the check valve on the fuel pump. (anything to that?) O2 sensor?
The car runs fantastic until it comes to a stop, then it stumbles so bad it will stall.
Is there anything a dealer service tech might be able to do that I can't?
I'm at my wits end. Any fresh ideas?