Hi,

Just bought a 94 Jimmy with the 4.3 Vortec (w) engine. The truck has a rough idle, and the truck surges at low speed. I've replaced the plugs, wires, rotor, and distributor cap. When I pulled the plugs I noted they were pretty well fouled on the passenger side. I also noted that the distributor cap rotates freely (clockwise) - which doesn't seem quite right.

Any thoughts?

 

Yea, check for a vacuum leak.
Check your pcv valve (make sure it moves freely), and check your EGR valve, EGR solinoid. Sounds like a vacuum issues to me.

Or it could be a partially plugged fuel filter, replace it and run some sea-foam through the gas tank. Burn 10% Ethanol blended gas. The ethanol helps keep the fuel system clean.

Wouldn't hurt to replace teh air filter as well. A plugged air filter will give you crappy gas mileage.

 

The passenger side only plugs fouled indicates that side is having problems. There are threads that indicate that the fuel pressure regulator maybe leaking fuel on the passenger side. But you have to remove the upper intake to be sure or maybe the throttle body and look through with a flash light. If you see shiny metal then fuel is washing down the intake manifold and you are getting to much fuel in those cylinders...

Is it just the cap or is it the "whole" distributor? If just the cap then you need to figure out why, might need to replace distributor. If it is the whole distributor then check the hold down clamp, then try to retighten or repair as necessary.