Vortec 454 EGR problem?
Hey guys. I have a problem with my 1996 Chev C-3500, Vortec 454, dually with 133,000 miles. It hauls the race trailer. It chugs like it's missing at steady state cruising. It idles fine and accelerates fine with no missing, just chugs at steady state at any speed. The faster you go the worse it chugs. Code reader said EGR problem. I put in new plugs, wires, dizzy cap and rotor, and put in a new EGR valve. Also cleaned the MAS. Took it for a test drive and it did the same thing. Chugging at any steady speed. Called a buddy (pro mechanic). He hooked up his high dollar analyzer. It showed no codes. Then we took a ride. Analyzer showed no missing while the engine was chugging away. What the heck? He suggested unplugging the EGR valve. We did that and the chugging went away. Truck runs great. Of course I now have a check engine light. Any body ever run into anything like this? It has us both stumped. Any help would be appreciated.