Rough idle once engine is hot

By forstr
May 28, 2004 in Gen III & Gen IV V8 Engines (LS-Based)

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forstr

Posted May 28, 2004

Truck idles very rough when it gets hot. Did a tune up and noticed that the NO. 8 plug is fouled real bad...still runs the same. Here's what I'm thinking, maybe someone can offer some tips.

1. Timing off (affecting fuel mixture)

2. Vacuum leak affecting manifold pressure/injector

3. Valves out of adjustment

4. Bad rings/valves

5. Bad coil (although it only affects one cylinder?)

6. Bad O2 sensor? Probably not...just throwing it out there

Please help ASAP!

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