I have a '95 c2500. The CEL comes on intermittently but codes 31, 32, 33, have been locgged on the computer. I have done some vacuum testing on the EGR and solinoid which seem to put vacuum on and off appropriately. I also seem to be getting a "stumble", sometimes at low rpm; sometimes at highway speeds. The whole problem seems to get worse when I have my boat in tow, ie: CEL on more frequently and more "stumbling". I note that the CEL usually comes on when the engine is lightly loaded. What I mean to say is ... The CEL does not come on until the truck is at speed and just maintaining.
Vacation is coming on Sunday. I hope it won't leave me at the side of some road, hitchhiking.
Any assistance is appreciated.

Read the FAQ sction. You're most likey looking at troublshooting the vac system and the fuel supply system.

Thanks ..I'll give it a try.

I got those codes a while back and it was the harness to the EGR solenoids had broken wires AND a bad EGR Vent solenoid. I had to repair the EGR harness and replace the solenoid. But now.. I just run an F prom :ro)