The gauge seems stuck and it won't move, I hear a weird buzzing when the gas pedal is partially open. I have never had this type of problem so I don't know what to do about it. Should I just get an aftermarket gauge to replace it?

 

An aftermarket gauge would let you know if your original gauge is being retarded or if there's actually something wrong. I would wait a bit though, someone here might already know what's going on.

 

If it doesn't move at all, you need to check the vacuum line to the boost sensor, and boost sensor itself.

If you haven't done so yet, download the FSM for free at XenonZ32.com Reference