hey guys, i have a 94 z28 with a 6-speed and the car runs great around town but once i get on the highway and get it into 5th gear, if i step on the accelerator too fast the RPM's go up but my speed doesnt, and i can feel the car chattering when it does this. but if i slowly ease into it, it has all the power it should. thanks guys.

 

You need a new clutch.

 

at first i thought it might be a rev limiter or speed limiter, since it doesnt do it at low speed or rpm.