I have had the most luck using the throttle stop screw (front side of the N/A throttle body) to get a good idle on a fully emission's stripped car. The top screw does not really do much. And yes you will be adjusting on that TPS constantly to make the car idle properly. It might still hunt on you. My race car surges like that all the time...

 

A series five with no TPS or mal adjusted TPS or codes showing OMP codes will result in LIMP MODE.
Meaning it ain't a gonna run right til the OMP gets fixed and no OMP codes showing no 'mo.

See LUBRICATION section of the FSM for OMP code fixing.

 

A few posts back i said i had fixed all the Check Engine Light error codes, everything is fine i just have to dink with the idle now.

 

Ok so is there any way i can get to all 3 of the idle screws without taking the TB off? That is the only way i have found to be able to get at one of the back ones, i have been slowly tinkering on it for a couple months now and I think one of the problems is a vac leak, the main vac hose where it connects from engine to break booster is cracking. I also think that my injectors might be leaking because i will be cruising around 30 and it will buck a couple times then stop, wait a while and do it again, mainly when on light throttle.

 

Ya, run down to the parts store and get a slice of hose to fix that brake booster line. Those injectors are kind of a PITA but they do leak there like you're thinking and develop a vacuum vacuum leak that acts like what's going on.

The butterflies can be adjusted as well, (which you probably already know), the PO may have messed with them though. I would first set the idle to 1000 by adjusting the butterfly stopper that's connected to the thermowax, then bring the idle down with the top screw. Basically set the two extreme's first. The top screw is only good for a few 100 rpms of adjustment on the S5 IUM. Oh, when/if you pop that UIM off, check to see if the PO removed the vacuum lines from under the injectors. Those are some sort of "injector fuel airrator" ports, but are sometimes mistaken for emissions junk. They should be plugged back in....check out the vacuum line diagram to get a better idea. Of course the check connector should be jumped before setting all this; post results.

 

Okay, i know i haven't been on in a while and this is an old thread but here are my updates. Not really much has been done with it regarding this, I do not have thermowax or really anything on the TB. as i said it was stripped by the PO but now that i am driving it again, other projects going on, I really want to get this thing fixed so it will idle properly. As I have not worked on this car much i have pretty much forgotten everything i have done with it so far. so here is what it does now. No CEL, when i get off the throttle coming to a stop sign or whatever it will bog to about 500rpm then jump to reving between 1100 and 1600, and some very unlikely times it will smooth out at 1150ish few a couple seconds, then go back to surging.