1995 Chevy S10 pickup with rough idle. just happened over night. module, coil, distributor, timing?

Question

1995 Chevy S10 pickup with rough idle. just happened over night. module, coil, distributor, timing?

Answer 1

Look at the spark plug wires to see if there's spark leaking/jumping to a nearby ground.

  This is easiest to see in the dark with the engine idling.

  If so, replace the whole set of spark plug wires.  

Answer 2

bad gas, fuel filter, spark plug,... add a bottle of fuel treatment change the fuel filter get new plugs... would be the first things to replace....module, coil, distributor, timing  would be the last things to check

Answer 3

someone stole your chevy engine, and replaced it with a ford engine

Answer 4

egr valve stuck open is my guess