Bear with me because this is a tough one to explain without being able to show. Recently I've had a problem with the tii where it kind of sounds/feels like its running on 3 cylinders, even though most of the power is still there. I checked the wires and they all worked so I thought it may be worn plugs, well I just changed those and they didn't really fix anything. The car runs smooth at idle and the problem only occurs under load, it kind of sounds like the Boxer engines in the WRX's or STI's if any of you are familiar with Subarus. It still cruises fine in the freeway though you can hear the problem but not feel it which is probably because I'm just cruising. The car will backfire from the exhaust occasionally at idle and under acceleration, during one of its backfiring sprees (at idle) I decided to pull the plug wires again (don't ask why) and found out that the backfiring would stop when I pulled the #4 plug. Now I'm new at this stuff so that's why I'm turning to you guys. I'm also thinking fuel injector pump maybe, but I wouldn't take anything I say too seriously. Anyway hope you guys can help, thanks.