Weird Misfire on 3.4L

[chevypower05]

please help, for a while i have had this weird misfire in my 2000 monte carlo 3.4L. At first, the car would rock back and forth, and the rpm marker would flicker between 2000 and 3000 really fast. I took it to the shop, the computer showed 2 coils and 3 spark plug wires were burnt. So they fixed those, and on the way home from the shop, it did it again. But this time, for only about 1 or 2 seconds, it rocked back and forth less aggressivly, and the rpm only flickered between 2000 and 2500. It will do it one day, then nothing for a couple of days, then it will do it again, no matter if im accelerating, braking, or just cruising, anybody have any clue what could be wrong, thanks a bunch.

[geoffinbc]

Maybe the last coil pack.

Plugs could be a culprit too.

[chevypower05]

follow up question on weird misfire

do you think it has anything to do with me having put bosch platinum plugs in the car, other than the misfire, the car runs great.

[slick94prix]

From what I've read on several message boards, you just want to stick with AC Delco plugs. There pretty much the best for these engines.