what else can I check on my 4.3 engine that runs rough at low speed runs fine and faster speed

1991 GMC SONOMA
184,000 MILES
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PEASANT
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1991 gmc sonoma sle 4.3 4x4 runs rough at low speed runs fine and faster speed, I've replaced plugs wires cap rotor, air filter set the timing, cleaned venture carbon with cleaner and tooth brush also replaced Idle Control Valve. I've checked all the vacuum hoses and did the throttle body gasket check thing with carburetor cleaner...not sure what else to do... can you help...
Thanks...
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Jul 20, 2012 at 4:18 AM
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KHLOW2008
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If equipped with EGR, check the system.
Jul 20, 2012 at 5:00 AM
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PEASANT
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EGR system checks out ok...I'd like to add it runs rough when below operating temperature I've also replace the temperature sensor...once it's up to operating temperature it idles and runs fine...what next...
Jul 29, 2012 at 4:59 AM
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KHLOW2008
  • ✓Experienced Mechanic
  • 41,812 POSTS
Have the compression checked and valve clearances readjusted and retest.
Jul 29, 2012 at 7:24 AM
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