How exactly do you test the injectors? I pulled off the intake mani and put a multimeter on them. All of the injectors showed 12.9-13.1 Ohms. Is there any other tests i can do on them?

I read the S4 FSM, and it doesnt really say much. Have you guys tested them before?

Injectors are very simple. You put 12V across the pins and they open. Remove it and they close. If they don't do either of those things, they're no good...

Here's a longshot:
The ECU is programmed to cut fuel on deceleration and it does it in stages right near closed throttle if the revs are above 1500.
If the TPS has a bad spot in its sweep of values, the ECU could briefly think you're closing the throttle.

I'd start by getting a spray can of CRC 2-26 contact cleaner & lube. (Home depot electrical dept)
You can work it in the TPS plunger.
You can pry off the AFM cover & clean the inside contact brushes. Then reseal the cover.