2000 Chevrolet Malibu • 11,200 miles

I did a lower and upper intake manifold gasket change on 3.1 litre engine. I have completed your 10 step trouble-shoot process and still having trouble.
Yesterday, when I started the vehicle, it reved very high (2500 rpm) and then would quit. I have replaced the TP sensor and IAC sensor. Now, it revs too low and quits. I did not compress or pull on IAC sensor pintle.I just put it in the throttle body straight from the box.
Also, when the engine quits it makes a "ch" sound. Such as when you say "church". It's a quick "ch". I'm worried about that sound. When I replaced the gaskets I did have to take out the push rods. The manual said keep these in order because their different lenghts. I'm pretty dang sure I did. Do you know the reason of the "ch" sound? It did it while it reved at 2500 rpm. And again today when it could barely idle. Also a gas odor.
Thank you for your help.

October 17, 2012.

The noise would usually occur when engine cuts off at a higher rpm than idling and is not a problem.

Did you clean the throttle body?

Oct 17, 2012.