Truck Engine Troubles

I have a 96 Chevy Cheyenne 2500 with the 5.7 liter 350 engine. The trouble is that when I get up to between 55 and 65 I’m getting a jerky feeling-like it’s trying to skip or jump time, or like it might have some kind of fuel restriction. So far I have replaced the plugs, wires, and fuel filter, and even went as far as buying a new timing chain, Gear, and gasket set, thinking the chain might be a little slack at the higher RPMs. It has more than 158,000 miles on it. Someone said it might be a head gasket. Any Ideas on what the problem could be?

The first thing I would do is to finish the tuneup you got halfway done with. Change out the distributor cap and rotor. Your problem could lie there. Timing chain and head gaskets are two of the least likely culprits for causing a problem like this. If it had jumped time or had too much slack in the timing chain, the engine would either not run or would run so poorly as to make it undriveable. Do you have a check engine light on? If so, what are the codes?

It COULD be a lot of things, and your CEL should be on… When it’s “skipping”, what happens if you floor it and keep it floored for a brief period of time?? Does it accelerate smoothly?

If you accelerate hard from say 20MPH will it move through the 55-65 range without any problems?

Or does this just happen at part-throttle cruising conditions…

Thank You for the feedback. This particular vehicle has a coil system instead of the usual distributor cap type of ignition. I’m not sure of the exact terminology. I have never had the check engine light come on.

When it’s “skipping and jerking”, and I floor it and keep it floored for a period of time it runs very smooth. If I step on it from about 20 to 30 or so and accelerate through to the 55 - 65 range there are no problems. It only does what I described when I am under part-throttle cruising conditions.