run a compression test with all the plugs out to see if all cyl. have near the same compression.. or put a vacuum gauge to a intake vacuum source with engine idling.. reading should 15-20 and steady. if you dont have a gauge put your fingers lightly in the holes with the plugs out and spin the engine you should feel a push..then check back
I plan on running a compression test, waiting to get the tool in the mail (figured it could hurt to have one around so I bought one instead of borrowing one from one of the FLAPS). I DO have a vacuum gauge... when idling (the engine wasn't warmed up prior to the test though), the guage pulsated between 13ish to 17ish
If you're sure you're getting spark to the end of the wires then I'd say you've got 3 bad plugs. I've bought brand new AC's before and they've gone bad inside 100 miles! You wouldn't think they would go bad but they do. Change those 3 plugs out with new and you'll fix your problem.
I will do that tomorrow on my day off!
