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  1. #1

    Smile 2001 GMC 6.0L Rough Idle and Almost closed throttle Miss No Codes

    I just purchased a 2001 GMC 2500 hd with only 20,000 miles on it. Looks and drives just like a new truck. At idle it seems to run smooth and then stumble abit, Then it returns moments later??? How it corrects itself is a mystery. Also after the truck shifts out and low rpm only slight throttle it seems to have an engine miss more like a lean stumbling feeling. All other positions runs great! I have replaced the gas filter, air filter, spark plugs, wires and cleaned the mass airflow sensor. No difference???? Also no codes?? Any ideas would be very much appreciated. Thanks!!

  2. #2
    Jr. Engineer
    Join Date
    Feb 2007
    Edmonton, Alberta, Canada


    seafoam, tune up then see what happens

    1993 K1500 Suburban 350TBI, 378,486KMS on frame, 49,000KMS on Drivetrain. Lots of mods, built for haulin trailers and haulin @$$ :)

    2000 K2500 Yukon XL 6.0L Vortec 252000KMS custom CAI, and exhaust...but not done yet.

    "If you are dumb enough to do something you don't know how to do, and can't do it safely then WHEN you get hurt its your own fault...BONEHEAD"

  3. #3


    Tune up did not change a thing..... How does seafoam work? Any other ideas??

  4. #4
    Jr. Engineer
    Join Date
    Feb 2007
    Edmonton, Alberta, Canada


    There are a bunch of threads on here about seafoam. but watch the "How to use" video on their website, and its the best way ive found to do it.

  5. #5
    murdog94's Avatar
    Join Date
    Feb 2008
    Cloquet, Minnesota, United States
    Blog Entries


    Pull the IAC (idle air control valve) out of the Throttle body and clean it out and the pathway for it out. Sounds like a classical symptom of gummed a up IAC.
    I also would for sure do a seafoam treatment. But when you put it into the motor let it sit for an hour or so (they reccomend 15min or something) after you have done that take it for a drive and you should have all the carbon blown out of hte top end of the motor.


    1997 Chevy S-10 Blazer 4X4 with 330K miles and counting (Hunting rig).

    2009 Saturn Aura XE (wifes car)

    2011 F-150 Crew 4X4

    "Hold it to the floor till you see God.... Then Brake!!!!"

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