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    Default 1996 GMC sonoma stalling at 55mph?

    have a 1996 GMC Sonoma 4.3L with 5 speed manual transmission. It has 200,000+ miles on it, but all maintenance has been done since bought new. In the past six months I have installed new fuel pump, new fuel filter, rotor cap and button, new spark plugs and wires, new TPS, new pulleys and serpentine belt, ran seafoam through the gas tank and through the vacuum line. My problem is at 55 mph while in 5th gear the motor will loose power and run really really rough like its trying to die, then magically it picks back up and runs like a champ. I am thinking it could be the EGR, Mass Air flow sensor, or something like that. The check engine light does not come on. Any ideas? Thank you.

    Also, this seems to be more of a problem when the engine is good and warm and under a small load, like going up a decent sized hill. What is really frustrating is that it runs great other than this. Im tired of throwing parts at it.
    Last edited by JIMBOBHOG; 08-15-2012 at 03:05 PM.

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