1989 5.7L/700R4 K2500 4x4 (rebuilt trans this spring). Ok. Fuel pressure at 11psi (specs at 9-13 psi). Smoked the vacuum system-no leaks. Base timing is dead on (0 degree BTDC). Hessitates on tip-in (warm/cold-light throttle). Disconnected EGR-runs better, but no change on tip-in. Idle speed is w/in specs. During the first five minuets of warm-up, it idles rough, and lopes horribly. Under load (reverse), vehicle will die. Pulse-width/timing is correct. There are MANY cliffs around here...lol. Any suggestions? Also, any suggestions on torque lock-up around 35-37 mph?

 

Yes, all new plugs/wires/rotor/cap-acdelco (love OE quality). Also, replaced the ignition module. Still stumped! But thank-you anyway.

 

I am suspicious of the IAC, but it doesn't make sense hot/cold. Also, the computer is commanding the EGR on/off at random intervals. I suspect the solenoid to be part of the problem. Have you heard of any grounds or anything related?

 

You know, there may be something to the ECT...I shall check that tomorrow. Thank-you for your response, by the way!

 

Pop off your distributor cap and verify your new rotor is clean,tight, and dry. Inspect the new cap for carbon tracking and cracks. It'll take ten minutes and won't cost you anything.