1990 GMC C1500 Chug and Studder

1990 GMC C1500
190,000 MILES • V8 • 4WD • MANUAL
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MGEE
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HI, I replaced the spark plugs, wires, distributor cap and rotor. I replaced the fuel filter, O2 sensor, IACV, air filter and moved the starter so that the wiring is under the heat shield and protected from moisture. After replacing the IACV, the truck stopped chugging and studdering...Then it came back. It only happens when I have my foot on the gas at about 1/4 pressure and the engine is up to normal operating temperature. When it is in neutral or coasting in gear, it does not happen. The TPS is the only thing I haven't replaced, as well as the injectors. Also, the "Check Engine" light does not always come on when this happens. I am not sure if the money is worth spending, because now it feels as though I'm simply throwing money at it and hoping it works.... Thanks for your help.
Sep 12, 2010 at 10:52 AM
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JACOBANDNICKOLAS
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Have you had the computer scanned?
Sep 14, 2010 at 10:47 AM
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MGEE
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No I have not scanned it, because I was told the "Service Engine Soon" light has to be on when they scan it and it doesn't always come on...
Sep 15, 2010 at 12:09 PM
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JACOBANDNICKOLAS
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I understand. However, when the light is on, it needs to be done. It could be caused by several things. Without the computer being checked, it becomes a guessing game.
Sep 15, 2010 at 9:16 PM
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MGEE
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How much can I expect to spend asking a mechanic to scan my computer?
Sep 16, 2010 at 1:12 PM
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JACOBANDNICKOLAS
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Most nationally recognized parts stores will scan them for free. That is where I would start. It would be cheaper to purchase your own OBD II scanner that pay a mechanic.
Sep 16, 2010 at 1:21 PM
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MGEE
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Ended up selling the truck and cutting my losses before having to shovel around it all winter!
Apr 9, 2011 at 3:29 PM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.