My 1990 Iroc 305 TPI 5 speed has developed this stuttering and what feels like a misfire. It stumbles (not all the time) from idle, but at about 3000 RPM it just doesn't want to make spark it seems. It misses. I just put on new plug wires, the distributor cap had some nasty green crap in it that I tried to clean out as best as I could. It seems my car eats up distributor caps. This is my third one in four years. It always gets a carbon build up like that. Is this the problem?

 

Doubtful. I'd try replacing the ignition coil.

 

The coil is now an MSD Blaster. When I pulled the coil wire off, some nasty white stuff came off with it. Is that an indication the coil is bad? Is that why I get carbon build-up? Because the spark isn't hot enough?

 

i would say the white stuff is corosion so be sure and clean it up goog and put in some electronics goop ( local auto parts place) i wouldnt blame the coil just yet i would check to be sure you dont have any wires on the exaust then check you timing then you may want to check fuel presure at that rpm(3000) if you still suspect the coil using an ohm meter and run the coil check you repair manual for the correct ohm range ..also what brand plugs did you put in ...if they arn't NGK i dont use them good luck

 

Yesterday when I replaced the wires, I went ahead and re-timed the car, no wires are on the manifolds (main reason I replaced the wires and moved the distributor around), I replaced the coil today and that seemed to have been it, I'll know in the morning for sure. But on the test drive, it was okay. As for the fuel pressure, it worries me. I'm almost sure that the pump may e stepping out a bit. I don't hear it when I turn the key on, plus it's 113,000 miles old. I was going to do the coil check procedure, but I couldn't find my brother's chilton's manual. I have a crappy Hayne's that doesn't tell me anything. Thanks guys!