I Have a 1993 k1500 5.7L 4x4 with 135,000 miles. While driving the engine develops a surg/loping/stumbling problem roughly between 1000-1500 rpm. I can accelerate through that range with no problem, it's just when i hold it between that range it will develope the problem. Also get a Check engine light when the truck gets up to operating temp. Everytime I try to check the code it only gives my one flash, not sure if it's reseting itself everytime i turn the truck off. I figure it's a sensor but have no idea where to start looking. Anyone have any ideas please lets hear them.

 

Hmmm it seems my truck has Begun the same problem just without the stumbling/Surging ect..But my check engine light has started coming on ONLY when at operating temp. when i turn my truck off and back on it will not come on for like 5 mins then stays on again untill the truck is turned off..I havent try to test the code..

 

get the code scanned. little problem now could turn into big problem down the road. it could be you throttle position sensor

 

I'm thinking maybe the same thing. The light isn't coming on untill it warms up because it's running open loop.

 

93Chevyman, I've had the same issue with my truck for over a year, just until lately have I decided to do something about it. Check out my post on 3-9-10 "stumbling problem", several people responded with suggestions. Mine does the same thing during low RPM if you lightly keep your foot on the gas. When I do this it either jerks back and forth like it's running outta gas or it does what you describe as surging, where it accelerates and slows down continuously. Now when I let off the gas, it sounds like it's going to die, but it never does and returns back to idle. The funny thing is the check engine light has never come on and I know the light works because it comes on when I start the truck as it should do. Yesterday I tried to take the EGR valve off and clean it but I couldn't get a socket wrench beneath the valve and loosen it, too tight of a fit. Also, I noticed that the end of the bolt that holds it on looks like a torx pattern??? Maybe I don't have the correct tool to loosen it?? I don't know? Anyway, I'm taking it to a friend tomm to see what the problem is. I'll let you know.