i have a 90 s5 131k miles 1k miles on fresh rebuild.

it began driving fine just a slight high idle 1.5-2k rpms which i knew was the tps... so it didnt bother me, and now one night she began to idle at 3k rpms and then would go back down to 750-1k rpm.. The car also hesitates past 6k rpms like it bogs.

NOW its idling at 5.5 k on start up and then drops back down to 3.5 - 4.5k rpms
Ive unplugged the BAC and nothing happens no change in idle, ive even unhooked the vaccuum lines on the intake and the car doesnt even stall.. kinda making me think it could be a vaccuum leak but i cant hear any leak at all no hissing or sucking noises.

I was thinking maybe the cam adjusting screw??? any thought would be great thanks guys!

 

Alright i took everything apart and it turns out the injector diffuser was leaking tons of fuel... My entire engine bay was soaked in fuel! fortunately it didnt ignite =D

Soo the diffuer was installed backwards Oring sealing against Oring.. when i removed them they broke =[[ soo i just ordered me up a new set, and i just need to wait to put it all back together and hope this is what caused the extremely high idle. the car literally accelerated on its own without me giving it gas all i needed to do was shift into the next gear.