I searched the forums and couldnt quite find what i was looking for, everything i found was just at highway speeds. My 94 camaro does fine at highway speeds but at 75 im only at like 2500rpm if i back off and im just cruising at 75 and my rmp drop to 2k the car starts to shake and the only way to get it to stop is to give it more gas and speed up. it does it at any highway speed if it hits 2k 75 is just an example since thats what i normaly go. i figure if it where unballanced tires or something it would do it all the the time but mine is just at 2k and it smooths out if i accelerate. any help is appriciated.

 

do you have the two piece driveshaft? i would look at the universal joints and if you have a two piece driveshaft look at the carrier bearing.

 

I would start off with balancing the tires and an alignment, also check your transmission mount...