i have a 98 camaro ss. automatic transmission, hard top. and this is one of the few cars of this body styles with practically no options.
for some reason when the rpm's hit 2k and up this strange vibration happens and it will "pulsate". the vibration will pulsate in a manner almost like the vibration has a vibration. you can feel it while driving down the road also. the vibration will humm like its constantly going from a small vibraion to an extremely noticable vibration. when the rpm's rise the vibration and the freguency of the "pulsation" will speed up.the car did this when i bought it at 70k miles. i put new plugs and 8mm wires.plus for some reason the guy before me cut on catylitic converter off but left the other there. i cut the remaining one off only to find it hollowed out. any help would greatly be appreciated.

 

try checking the u-joints

 

haha ok I had this problem on mine as well, is it just noise? check the rear wheel well compartment in the hatch where the spair tire is located. If anything is loose down there it will cause a crazy annoying vibrating noise... Let me know!

 

if u feel it in the seat of your pants or the shifter its probly the ujoints. do u have a poly trans mount. they will magnify vibrations.

 

I have a similar vibration, just bought the car, old owner replaced everything imaginable so the problem is internal to the engine poss. slightly bent rod... If you find anything else please post it. Don't worry it runs fine and has plenty of power. just vibrates at 1300 and about 3000

 

dave is the trany mount a poly mount? like this.

 

yea it has the poly trans and torque arm mounts

 

change the poly mount to a stock one. stock mount (10 bucks) is a bridge type and isolates vibration., the poly trans mounts magnify vibrations really bad. ploy tourque mounts work great have one on mine.

 

u will not believe the difference.