General Maintenance & Repairs - Shaking/vibration at high rpm.

I really don't know how to explain this but I've got this vibration that'll kick in in high rpms (4500-5500) and it'll do it with or without any load.

My friend's got a diablosport predator handheld that he hooked up and we revved it to the limiter and there was no deviation from the norm. I'm also not throwing a check engine light.

I really dont know how to figure this out, I've been told its the clutch slipping, but the feeling could best be described as a loss of power when the vibration occurs, which led me to believe a high rpm miss.

I could compare the vibration like driving over those ribs on the side of the highway, only not as loud. Also the car is backfiring alot, I've got new plug wires, new plugs, there is no arching (had that occur once before). And no SES light.

Anybody here have any idea on how to check or diagnose the problem.... I'm kind of stuck.

Also the car will kind of bog down if i shift during this, but will pick back up and then start again.

The car is a 1999 Trans am M6 with a lid and LT's and TD's as the only mods, with a texas speed tune.

Have you checked the coil packs and all grounds and wires? its gotta be a spark issue if its a miss and thats what it sounds like it is.

As far as the coils, I've had one before that was arching and that problem went away when i replaced the wires and spark plugs.

How would i go about checking the coils? I've got a meter to check the resistance.

Actually, im not to sure on how to go about that, perhaps someone with more experiance with the coil packs will chime in. Well, could be an excuse to go with MSD's..