My rig is a 1990 trooper with a 2.6 l 4-cylinder engine in front of a 5 speed tranny. It cranks easily but runs extremely rich and will not idle w/o throttle being applied.After it warms up , it will stay running but will not hold a steady idle, varying by 200 to 300 rpm's. When I stop at an intersection,the rpm's will drop to about 600 and then come back to about 900, which is about where it hovers.Also, the engine feels sluggish, as if the timing were retarded but I hear valve clatter like with pre-ignition. HELP!

EVERYTHINGS for sale! what'll you give me for the kids?