in my 90 iroc the rpm gauge is stuck! every time it turns on the gauge goes all the way up and stays until i turn it off! the engine runs fine so whats goin on????????

 

It's broke. At least, that's the technical term for it.

 

Where does the needle sit when the car is turned off? Is it like 5000 or higher?
When you turn the key to the 'run' position - before starting - does it go around clockwise until it pins?
If so, I can tell you how to fix it, and it isn't difficult.

 

lift your foot up off the gas j/k but seriously im having a similar problem, when i go to turn it over the tach just jumps all the way up past the 7000 mark and stops b/c of the stud and stays there until i turn it off i just cant seem to figure it out

 

If the tach needle sits at 5000 or higher with the key off, and then pins at over 7000 when the key is turned on, this will work.
Remove the front bezel - 8 T15 torx screws
Remove the clear plastic lens - I forget how many and what size/type of screws.
Use your finger to turn the needle back down to the 0 to 1500 mark.
Test it, then re-install the lens and bezel.
Fixed

If the needle sits down near the 1000 mark with the key off, and pins when the key is turned on, you have problems elsewhere.