Mitsubishi Repair: 1995 Eclipse misfires, vacuum leaks, head gasket

Question
I have been noticint that whenever \i head up a long grade between 70 and 80MPH that the car would have a slight misfire, just enough that I noticed it. Yesterday I started the car and there was a dead miss, very noticeable. I drove all day because I had to. I discovered that the #2 cylinder wasn't firing. Swapping the plug wires had no effect.

My guess is that an injector went bad. The car has 240K miles on it. The engine had a valve job about 3 years ago.

I appreciate any feedback. Hope it's not a valve or head gasket!

Thanks!

Answer
Michael: I am going to pull this right out of my car repair book. I would say one way you can tell if your head gasket is leaking might have water in the oil or the car smokes a white smoke. My book says this about engine missing throughout driving speed range... fuel filter clogged, low fuel output at the injectors, first try cleaning the injectors, faulty or incorrectly gapped plugs, incorrect ignition timing, cracked distributor cap, leaking plug wires, faulty emission system components, low or uneven cylinder compression pressures, weak or faulty ignition system or vacuum leaks and it is the same for the engine backfires. But adds damaged or worn lash adjuster and or valves sticking. I always try the easy things first and work into the harder things. You said you swap the plug wires but had no effect. So maybe it was more the distributor cap. No matter the miles if you have taken good care of the engine and the car; it might not be something so bad as a valve or the head gasket. Hope this helps and good luck!