1994 GMC Sierra rough idle and missing while driving

Tiny
JIMELAINEDAVID
  • MEMBER
  • 1994 GMC SIERRA
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 136,000 MILES
It does not do this every time I drive it but when I do it stumbles and back fires. 2 months ago it started this I replaced plugs and wires. It worked for a few days then it started it again. When it does this if I let it sit for a few hours or so it MAY start and run fine, then next day out of the blue it starts this again.
Sunday, February 14th, 2010 AT 5:38 PM

1 Reply

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Check and test all the following below:

Oxygen sensor
Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)
Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
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Monday, February 15th, 2010 AT 5:51 AM

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