Throttle Body
 

Can i replace the stock throttle body with

GM ACDelco - New LSJ Throttle Body #

or do i need the adapter plate too?

Yes and yes

If you aren't an LSJ, what ^she said is correct. You would also need a tune for it. Also, shop around because you can find them cheaper than that

need more info on which car you have

It's an 06 cobalt ss, engine light is reading bad TPS was just looking to replace it

What motor ss?

2.0 ecotec, just the stock one.

If it's the 2.0 supercharged then all you need is the throttle body, no adapter and no tune, because that's your stock one.