92C1500

I need some advice on where to begin with this one. I have a 1992 C1500 Silverado with the 4.3 V6. When I hit the accelerator the car falters and then recovers. This problem has become gradually worse, beginning as a slight falter when the engine was up to temperature and accelerating up a hill.

The engine had a full rebuild after a blown head gasket a couple of years ago and hasn't done high mileage since then. The falter doesn't occur immediately from a cold start.

I've had some issues already:

1. Since the rebuild I get error 43 (a problem with the knock sensor) after driving for an hour. Engine ran fine though, so I haven't done anything with this.
2. If I screw the IAC valve in all the way the revs drop and the engine stalls when I put it in gear. It did this before the rebuild. I've changed the valve and still get the same issue. I've followed the manual to re-calibrate with no success. Engine ran fine with the valve backed out a few turns.
3. The "SERVICE ENGINE SOON" light doesn't always come on on the dashboard when you turn the key before starting the engine. If I keep turning the key on and off, it eventually comes on.
4. The exhaust came lose from the manifold on one side recently. I've fixed this already.

I found I had some OBD codes. I got 32 - EGR valve, 43 - knock sensor and 44 - Lean exhaust. I wasn't sure how old these are or if maybe they related to the recent exhaust leak, so I disconnected the battery to reset and tried again. Engine faltered and I got no codes.

I'm in the UK, so finding a professional with experience of these vehicles isn't easy. I do a lot of wrenching myself, but usually on carb engines - my experience with the TBI set up isn't up to much.

Suggestion on where to start please!

JoshNix

Might possibly be head gasket again depends check and see if your plugs are wet.