Questionmy 94 k-1500 5.7 has a hesitation or stumble problem.idles kinda rough but smoothes out eventually. the real problem is when you get up to around 60 mph. then it stumbles for a second, but then picks right back up and then runs ok for about a mile and then does it again.this only happens early in the morning, when it rains, and late at night. i have replaced the fuel filter, distributor cap, rotor button, spark plugs and wires, ignition module, pick up coil, ignition coil, vacuum hoses,egr valve solenoid, throttle position sensor, idle air control sensor, oxygen sensor, fuel injector, fuel pressure diaphragm kit. i am at a total loss.
AnswerAre you sure the problem is with the engine? Could it be with the transmission when the vehicle goes into lock up? It's common for the truck to go into torque converter lockup between 45-55 but in some cases if the trans is old it may lock up at 60-65.
It sounds to me that you have changed everything that can cause the engine, electrically, to hesitate. I will do some more research on your problem and let you know what I come up with
Jimmy
