Mitsubishi Repair: misfire, cylinder compression, carbon residue

Question
my 95 eclipse rs 2.0 manual in idle,  sounds like run in 3 cylinders on the road it misfire , i did replace wire and spark plugs and also the coil still the same , i notice that the 4th cylinder as more carbon residue in the spark plug , it is possible that the problem is the timing belt skipped 1 or more tooth or is cylinder compression ?
thank you
giuseppe

Answer
Giuseppe,
I'd recommend running a compression test to make sure you are getting the proper compression in each cylinder. If only one or two plugs in a set are fouled, it is a good practice to check for sticking valves, a cracked distributor cap, or bad secondary ignition wires. Fuel injectors that malfunction can also lead to this condition. Other causes include weak ignition system voltage or an inoperative pre-heating system (carburetor intake air) or poor cylinder compression.
Good luck!