Replaced my intake manifold to fix one problem only to have another one arise. Now when the car is in drive, My foot on the break,& the a/c on the engine when at a stop sounds like it misses a step or stutters at ideal( around 900 rms). once i turn the a/c off at a stop the problem disappears
I had this problem when the compressor for the A/C was failing and seizing up. Please check this out first at a competent A/C shop. When the unit seizes up completely the drive belt will smoke and destroy itself. Don’t wait that long!
The problem might be caused by a dirty/faulty Idle Air Control valve.
The IAC valve controls the engine idle speed under all conditions whenever the accelerator is released at a stop.
So for example if you where to turn the steering wheel at a stop, the IAC valve adjusts the idle speed for the load the power steering pump imposes on the engine so the engine doesn’t stall. It does the same thing when the AC is turned on and the compressor imposes a load on the engine.
If the IAC valve fails to go to the proper position for the idle condition, or the IAC valve is dirty, the engine idles rough or may stall out.