Driveline Shudder in 2000 Mustang GT

Heya folks,

I'm hoping somebody might be able to help me out. I have a completely stock 2000 Mustang GT 5-spd with 89,750 miles. The car has been fairly bullet proof with the exception of an IAC that went bad and kept stalling the engine whenever I pushed the clutch in, and a corroded fuel filler neck which kept setting off the "Check Engine Light".

I had the fuel filler neck replaced last week. But after I picked the car up from the shop, I noticed that when cruising along in 5th gear at 40 mph (which is around 1000 rpm) whenever I pressed the gas pedal, the car would start to shudder. The shuddering would get more violent if I go to WOT. I also noticed the engine would start making the same sound it does when the traction control kicks in.

The shuddering occurs in other gears at well, but at higher in the rev range, but it all occurs whenever I try to go from part-throttle (cruising) to WOT (accelerating).

Any clues? Any help would be greatly appreciated. I'm going to be installing a new exhaust set-up this weekend and I'd like to know if there's anything else I need to do.

Joe

Great job guys and thanks for the advice....you hit the nail right on the head.

Turns out the COP on the #6 cylinder went bad. It was misfiring and ended up fouling the plug. Had the COP and all the plugs replaced (preventive measure), and now she purrs like a kitten. Also had the other COP's checked and they're all firing perfectly.

Joe A.