94 gmc jimmy rough idle good top end?

[fishfarm4]

94 gmc jimmy vortec 6cyl. has rough idle , i changed plugs,oil,air filter and fuel filter , i cant see sparks at night on plug wires , im lost ,,,

 

[bajakma]

well you may want to finish the tune up replace the pcv and egr valves and clean the throttle body, but i must tell you GM had a tough time balancing that motor, they did smooth it out some with the counter balance shaft but still wasn't like their other motors.

 

[Angel C]

Maybe the wires were not placed in the right firing order. Check your manual. It can also be caused by a faulty vaccuum line.