I am having problems with my '96 2500 van (5.9L) w/4 spd auto. Starts good, accels good, but at cruising speed, (no load) it shakes & misses like crazy. Give it gas and it accels great. Does it in either 3 or 4th gear. I have replaced plugs, cap & rotor, pickup coil, & air filter. Same problem. It did run fairly good last evening at 70 MPH but detected a surging at interstate crusing speed. (w/cruise on)(Gas tank read about 1/4 full.) Any ideas?

 

I'm going to say your fuel pressure is too high. This could be due to a bad pressure regulator or the vacuum hose going to it is leaking.

 

What is the trans fluid level? When was it last changed and the bands tightened?

Also does it do it with the fuel tank full?

 

Alloro the fuel pressure regulator on this van is also in the fuel pump module in the tank, not on the engine.