I have a '90 Civic DX Hatch that I use as my daily driver. As I was crusing up a hill on the highway yesterday something stopped working and the car lost a lot of power and started running really rough. I made it home and determined that one cylinder is not running. It's not the wires, as I swapped two and it's still the same cylinder. I pulled the plugs and the bad cylinder was pretty foul w/ oil, but not coated. I installed some new plugs I had laying around, still not firing on that one cylinder. Distributor cap looks good. What next? I"m thinking the worst, as the engine has been leaking oil around the headgasket for some time. Any other suggestions of what to check? What kind of cost would I likely be in for if I paid a mechanic to re-build this engine or install a used one?