1995 GMC S15 spark still everywhere

1995 GMC S15
140,000 MILES • 6 CYL • 4WD • AUTOMATIC
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IINVNO1
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would this cause the vehicle to idle rough? Also on the highway it seems to run fine plenty of power and such but when we go hunting it loads up and when given gas black smoke pours out exhaust and most of the time will clean up. but sometime plugs foul out and need cleaned does this sound like a valve prob? Or spark?
Nov 6, 2008 at 7:52 PM
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MHPAUTOS
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HI there,

Faulty spark plug leads will arch out and cause rough idle and miss fire, replace with good quality leads and see how you get on.

Mark (mhpautos)
Nov 6, 2008 at 7:57 PM
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SWILLIAMS
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I would also suggest looking into the intake manifold for a leaking injector unit or a failed fuel line to the injector. The extra fuel caused by the leak would also cause those symptoms and is a common problem with the CPI units.
The good thing is that the unit is easy to get to and check. The bad thing is that the replacements are not cheap.
Nov 9, 2008 at 10:33 AM
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