I'm having the same issue. I just bought this car about 2 weeks ago and have been poking around here learning about it. I'm a moderator over on NICO and have been around cars for a long time.
The story: Car is basically stock, but was modified when my father in law bought this car a few years ago. It was put back to stock and has run fine ever since. 2 weeks ago I bought the car from him and it's been fine. Last night I drove it a half mile to the gas station to get my wife a drink. I got back in the car and about 10 seconds after I started it and it was idling, there was a misfire, the car started to run on 3 cylinders, and the MIL came on. I babied it home and left it till today. Today I took it down to my father in law's to scan the code. It came up as a misfire on the #3 cylinder, which was confirmed by unplugging the injector and no change in running. I pulled the plugs and they appeared to be the stock Iridiums, as well as the plug wires. I installed new NGK plugs, in V-powers, and new NGK wires. Running was greatly improved, and after clearing the MIL, it doesn't come back. BUT it still bogs under more than about 50% load. I think they were all gapped at .035, but my brother in law put them in, so I'm not 100% sure on that, as I was on the phone at the time.
Suggestions?
