Please help! Horrible idle!

[gsxcellent]

My idle is horrible and i can hear it missing, The computer first threw a cylinder 4 misfire (p0304) then soon after threw a multiple/random misfire (p0300). i have changed the plugs and wires and i have tested my coil. Gapped my plugs to .028. All is good with spark. Cylinder 4 sparkplug is VERY black with carbon showing rich conditions. I did a compression check just for grins and giggles and here are the results:

Cyl 1-195
Cyl 2-180
Cyl 3-185
Cyl 4- 195

I also have a cracked manifold and my coolant is very very dark. (not sure if those two problems have anything to do with my rough idle tho)

THANKS!

 

[prettyblue6bolt]

Have you checked the timing yet?

 

[98gst14b]

Maybe a bad injector or coil? Does it do it when its cold, hot or both?

 

[SilverJester]

Ever fix the problem?

Maybe a bad injector or coil? Does it do it when its cold, hot or both?

I've got a car doing the same thing only when it's cold. drive it a little bit, it warms up and then all it fine.

 

[pepsi21463]

Did you check your ISC? Vacume lines? Maybe some buildup around the throttle body?

http://www.dsmtuners.com/forums/showthread.php?t=191137

http://www.dsmtuners.com/forums/showthread.php?t=54439