[bleucamaro]

My '89 S2 is running rich off of idle. At idle, it runs fine (~800RPMs 14.7 AFR, smooth running). As soon as the TPS goes from idle to transition state, it goes full rich (8.2 AFR). I've done some searching and most rich condtitions point to a hanging injector, FPR or vacuum leak.

If it was a vacuum leak or FPR issue, would the condition feel like such a light switch?

There are several relevant modifications to the car that I've tried to rule out, including: 2 bar MAP sensor (outputs similar voltage to AFM at idle and just off idle), GM type intake temp sensor (similar resistance to AFM), Innovate LC-1 wideband w/ gauge, and I'm using an SMT-7 piggyback and can see live data on screen and nothing looks out of the ordinary.
I also have 55lb injectors (siemens, low impedence).

The change in mixture is definately TPS triggered and is night and day. Any suggestions?