Engine runs rough?

Tiny
FIGARI
  • MEMBER
  • 2003 GMC YUKON
  • 3.8L
  • 4WD
  • AUTOMATIC
  • 340,000 MILES
After the car sits for any length of time and is started up, the engine runs smoothly. When placed in Drive, and with moderate acceleration, it misses until I punch down on the accelerator. At that point, the engine runs smoothly again. I assume that oil is fouling the plugs. Would swapping out the plugs fix the problem, or would the same thing happen to new plugs? Any other suggestions on how to fix this problem? My vehicle is in great shape and looks like new so I do not want to buy a new car. Thank you in advance.
Monday, June 24th, 2024 AT 6:34 AM

1 Reply

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,884 POSTS
Yep, I hear ya, I would start by changing the spark plugs, coil wires and the ignition coils themselves. This is part of normal maintenance and should be done anyway. Here is a video to show you how, this ignition coils replacements are in the images below.

https://youtu.be/h3Jmg2HRVYk?si=zymAQJ_GQNIE0l3T

SPARK PLUG TYPE

A/C Delco part number .................... 41-974

NGK Part Number .................... PZTR5A15

Check out the images (below). Please let us know what happens.
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Monday, June 24th, 2024 AT 4:23 PM

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