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1988 GMC won't idle

Hey Guys I'm hoping someone here has some info on this EXTREMELY frustrating problem. I have an '88 GMC Sierra p/u 5.7 liter, Turbo 400. For a while now it will not idle properly. It simple dies unless I keep my foot on the gas. I have checked the plug wires, changed the plugs , dist, and rotor, changed the MAP sensor(diagnostic code was set), checked the IAC valve and coolant sensor according to the Haynes manual, changed the fuel filter and air filter, and run countless quarts of fuel system cleaner through it. I can hear the fuel pump running when I turn on the key. Most of the time it runs fine while driving, but occasionally it seems to have a miss and lack of power at lower RPM's. The engine and trans were rebuilt about 22,000 mi. ago. Does anybody know what this could be? Have I missed something simple that I should have checked? Any help is appreciated. Thanks!

Reply to
quark1150
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Check for vacuum leaks.

Reply to
Jimmie

First thing pull the TBI unit and check the gasket under it as I had one go bad on me a few years back and do the same thing.

Reply to
SnoMan

"SnoMan" wrote: > [quote:fe71f4c5da="quark1150"]Hey Guys > I'm hoping someone here has some info on this EXTREMELY > frustrating problem. > I have an '88 GMC Sierra p/u 5.7 liter, Turbo 400. For a while > now it will > not idle properly. It simple dies unless I keep my foot on the > gas. I have > checked the plug wires, changed the plugs , dist, and rotor, > changed the MAP > sensor(diagnostic code was set), checked the IAC valve and > coolant sensor > according to the Haynes manual, changed the fuel filter and > air filter, and > run countless quarts of fuel system cleaner through it. I can > hear the fuel > pump running when I turn on the key. Most of the time it runs > fine while > driving, but occasionally it seems to have a miss and lack of > power at lower > RPM's. The engine and trans were rebuilt about 22,000 mi. ago. > Does anybody > know what this could be? Have I missed something simple that I > should have > checked? Any help is appreciated. Thanks![/quote:fe71f4c5da] > > First thing pull the TBI unit and check the gasket under it as > I had one go bad on me a few years back and do the same thing.

Check the EGR to see its not clogged with something.

Reply to
DLMan

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