By pass air controll valve
 

My car wont rev up past 2 grand when my connector to the bac valve is connected but it only does it occasionally but i dont connect it it runs fine but with less power would i need a new bac valve

Check the BAC for internal leaking. Blow through the metal tube and see if air passes by the inner seal of the BAC. If it does, a new one, or at least another one is needed.

are you talking of it not revving past 2 grand on startup, or while driving?

take it off, throw it away, put on a blockoff plate. unless you have ps or ac, then you need it. sounds like its leaking. i got one you can have for 10 bucks.

pat