I have been fighting this vibration for a while now. at speeds of 90mph it shakes pretty bad. may be the front tires, I dunno.

But today I pulled up to a stop sign, and gave a little gas. at 2000RPM's the car shook way bad. I pull over shorty after and notice my belt is half off my idler pulley. If the belt is walking off, does that mean the pulley is walking off? It has an ARP bolt and is keyed to the crank...any ideas?

2002 MN6 corvette

 

There has been some cases of aftermarket pulley having problems, maybe its your case..

 

this is a keyed stock pulley

 

The bolt got loose... It happened to me.

 

I don't know squat about this, but maybe inspect the damper to see if the outer ring is coming loose from the hub due to rubber degradation.