94 GMC SUburban. 5.7, auto, 146,000 miles. Never have had ounce of trouble prior. Truck started to run rough as if plug wire was pulled off during operation or like maybe clogged fuel filter. Mostly when under load. I replaced fuel filter, plugs (platinum), wires, cap and rotor with no luck. I noticed like the stator (i think) was really rusted and pitted. I installed a new distributor, set timing. I still have the same problem, no better, except now at idle the engine surges, and when at a redlight the truck tries to lunge forward and will eventually cutout. What am I missing?

Dennis Mulford

• 1055 Answers
• Posted on Feb 24, 2009

SOURCE: 1997 GMC TRUCK IS MISSING AT ACCELERATION

timing chain is streched replace chain and gear set

SOURCE: Runs rough. Plugs, wires, cap, rotor, timing all

Two problems. First fix the leaking injector o'ring. And when you have the tbi off doing that check to see if the gasket under the tbi is blown out causing the high idle.

SOURCE: my 79 Chevy has rough idle/miss at idle but runs fine otherwise

It sounds like you have a vacuum leak or a carburetor problem. Check all hoses and the line going to the brake booster for cracks or leaks. Make sure the carb bolts are tight at the manifold. You can check for leaks using some carb cleaner. Spray around the base of carb while the engine is running, any leak will cause the engine to sputter when the spray hits it. You may want to look into rebuilding the carb or replace it. If its the original its a Quadrajet, they are not the easiest to rebuild but not impossible. If you rebuild it yourself, make sure to get the numbers off the carb so you can get the correct rebuild kit and accelerator pump. Plus you should replace the float when you rebuild since its 30 years old. A thorough cleaning of the carb is crucial before rebuilding. The fuel mixture screws have caps on them so they wont be altered after assembly from the factory. You'll have to remove those caps to remove these screws before cleaning. You can probably find some good info. on doing this at a good parts store. I hope this helps you.

SOURCE: 96 gmc vortec will not start

I AM LOOKING AT TIMING ISSUES OR INTAKE MANIFOLD LEAK.OR EGR VALVE STUCK OPEN.

SOURCE: my 1992 gmc sierra truck started running very

Bad fuel, bad air filter,PVC valve, EGR valve