I was looking to swap my entire tuned port system from my 87 gta to my 91 rs. I would use the engine harness and computer from the gta, as well as the tpi, heads, cam, and all necessary sensors. My question is, would the necessary items have power and would everything be plug and play or would the year difference complicated things.

The ecm sensors are pretty much the same for that era. I'd suggest you research swapping to a 90-92 Speed Density set up. It's just that much more refined.