I have a 94 s10 Blazer. It is a 4.3 with CPI. Recently it started running rough at idle speed. I t started out of no where. It was fine then I was going down the road at about 45mph and it felt like it was skipping, when I got to the light it was running extremly rough(almost choking itself out). The check engine light came on and it started to heat up. It has not been heating up since then but it still is running rough. I did plugs, wires, cap, and rotor and it is not any better. I thought the cat was plugged so I took that off. It is still no better. Does anyone have any suggestions at all? Please help.

 

I just got a 94 Blazer - with the same engine as yours - from my aunt. She had a similar problem where the "Service Engine Soon" light came on and the engine ran rough. Apparently it was the EGR valve, which needed to be cleaned or replaced. Don't know if that's what your problem is, but it might be worth checking out.

 

get your computer scanned at auto zone and that would start you off in the right direction. but it does sound like an egr problem.

 

Clean the tube that connects the EGR valve to the manifold out with carb cleaner, you may have excessive carbon build up

Also check the fuel filter, and run some STP Gas Treatment through the fuel system, you may have water in the lines or something