1998 GMC Yukon rough running engine

1998 GMC YUKON
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DAVE PITTS
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Engine Performance problem
1998 GMC Yukon V8 Four Wheel Drive Automatic

after the engine has been running 15 to 20 minutes it starts to run rough and will almost kill if sitting at a stoplight. Last year we replaced the fuel pump, filter, relay switch, plugs and wires. It starts and runs GREAT for the first 10 to 15 minutes, then she geats weird.
Sep 21, 2009 at 6:42 PM
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JACOBANDNICKOLAS
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Has the check engine light ever come on? Have you checked fuel pump pressure even though it was replaced a year ago? Here is a how to for checking pressure.

https://www.2carpros.com/how_to/how_to_check_fuel_pressure.htm

Finally, my other concerns would be a bad EGR valve or a plugged catylatic converter. Check both of them and let me know what you find.

Joe
Sep 21, 2009 at 10:12 PM
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DAVE PITTS
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Check engine light came on 1 year ago and I replaced the O2 sensors (2), recently the "Service Engine Soon" light came on. I replaced the cap and rotar and that went off. I did discover that a recepter hole for the one of the screws that holds the cap on was broken. I managed to secure the cap in place using plastic weld. I have not check the pressure in the fuel line, and I will look at the converter and the EGR valve and let you know.
Sep 22, 2009 at 10:24 AM
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JACOBANDNICKOLAS
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Is the distributor cap okay now? That could cause the problem you described.
Sep 22, 2009 at 10:32 AM
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.