I have a 1992 K1500 truck with 4.3 V6 engine with 225K miles and auto transmission. I had a problem that when while I was driving and deaccelerating, the engine would shudder. After returning to idle it would almost stall, and then smooth out. When accelerating or under power the engine ran fine. I replaced the timing chain and cam gear, as the chain had a great deal of slop in it.

It seems to drive OK now when deaccelerating, but sometimes when I come to a stop, the engine would want to stall, then it would recover to a smooth idle, just like before. It sometimes wants to do this also, even when in park in the driveway, when the engine is raced and returned to idle. I suspect I might have had more than one problem.

I am about at my wit's end, trying to figure this out. Can anyone give me any pointers on where to look for the cause of this issue? Thanks in advance.