Check your timing belt. It may have broken or jumped a tooth. If it looks worn, replace it, and be sure to retime the sprockets when you do it.
distributor cap and rotor
Look at the spark plugs-- if one has no wire at the top, that is the problem- there should be a wire from each spark plug to the distributor cap.
It's like missing the ball, thinking you've hit it, and then accidentally running around the bases in the wrong direction.
Diagnosis: Engine Won't Start or RunCheck related link below
If you've already removed the timing cover there are markings on the top and bottom gears. Make sure they are lined up before putting the belt back on (if it has a belt) most chevys have timing chains. Anyway, once you've done that and reinstalled everything; the timing is adjusted by loosening the bolt on the bottom of the distributor. Once you've done this, with the truck running slowly rotate the distributor in either direction until the truck is running smoothly in idle. Once this is done retighten the bolt.
if you're looking down at the distributor it rotates clockwise while running.
On the track the running direction is counterclockwise from 200 meters to 10,000 meters.
At 100,000 miles or if it is running bad or missing.At 100,000 miles or if it is running bad or missing.
I'm not sure I understand your question. The ignition module is suspect in this case and yes, it's under the distributor cap. You may also want to replace the distributor cap and rotor while your at it, they're cheap parts and hair-line cracks in a distributor cap can be hard to detect. If all of these fail I'd look at replacing the coil and coil wire to the distributor.
It is inside the distributor, it has three wires running to it, and it looks like a small black plateIt is inside the distributor, it has three wires running to it, and it looks like a small black plate
Did you replace the fuel filter?
check the harmonic balancer