What are the chances it could be MAP sensor, MAF sensor, thermal sensor, etc. Reason I ask is because it rarely happens until the truck reaches operating temp and if it does happen its almost unnoticeable.

Thanks Mark

Can you tell I don't want to go to a dealer? <img src="/forums/images/graemlins/scared.gif" alt="" />

COULD POSSIABLY BE ANY OF THOSE , I WOULD DOUBT THE MAF SENSOR , THOSE THINGS DON,T FAIL VERY OFTEN, SAME WITH THE MAP , CHECK THE MAP SENSOR , WHERE THE SMALL VAC LINE FITS ON THE BOTTOM AND CURVES AROUND TO THE INTAKE MANIFOLD , AFTER A LOT OF MILES AND YEARS THE HOSE TENDS TO COLLAPSE RIGHT IN THE BEND, AND IT WILL TEND TO MAKE THE ENG RUN A BIT RICHER DEPENDING ON HOW MUCH IT CLOSES, AND IT MAY BE RUNNING TOO RICH AT LOWER SPEEDS , YOU CAN TEST IT USUALLY BY RAISING THE ENG SPEED TO ABOUT 1000 RPM AND PINCH THE HOSE TOGETHER OR PULL IT OFF AND PLUG THE MANIFOLD PORT AND IT SHOULD IMMEDIATELY RUN RICHER ,THE ENG TEMP SENSOR WILL USUALLY HAVE AN EFFECT ON BOTH HOT AND COLD RUNNING, BUT IF IT IS THE ORIGINAL IT DEFINATELY WOULD BE WORTH TESTING , HOT AND COLD , MOST ESP IF IT IS EXPERINCING AN OFF IDEL OR MID RANGE STUMBLE , JERRY