I have a 1987 GMC Sierra Classic. It is sputtering, chugging, and stalling. I replaced the spark plugs and wires, distributor cap and rotor, and the fuel filter. It is still doing it. People have suggested a bad fuel injector, bad fuel pump, or even a clogged exhaust system (bad catalytic converter or muffler). I am running out of patience and money. Can anyone out there help?
What size engine in this thing?
Tester
Also check the EGR valve. If it’s stuck open, it will produce those symptoms. So will a bad ignition module (inside the distributer) Pull gently on the wires to be sure they are sound.
State the engine size.
Does it do this when the engine is cold too? Or does it gradually get bad as the engine warms up?
Not wenough information but if the vechicle not driven often consider adding seafoam to gas tank as it may be just gummed up. write more about how many mniles etc.