So after driving a few miles and coming to a red light, my RPMs drop from 1000 to 900 and then come back up.

Possible vacuum leak?

 

Yep, my idle is around 890 rpms or so. I had a big vaccum leak a couple of days ago. My car wa misfiring (at least it looked like) and idle was different everytime. One of the hoses was totally broken.

 

Here is the thread
http://www.audizine.com/forum/showthread.php?t=227741

 

If it so happens that what audiprotein said isnt the case i had that problem when my coil pack started going bad so id check that too

 

That could be several different things, the first thing to do is check the fault codes, pulling out the shotgun and firing parts at it won't help.

 

Coilpacks are brand new hitachi's.

 

I wouldn't get a CEL for a vacuum leak necessarily, would I?

 

^^^ I got one, actually 4

 

hey whatsup protein! i know i have b5.. but i had same problem. it was sludge build up. check your throttle body and connection. had to clean it out. there was tiny build ups that caused NO air to get through when idling. this causes the engine to "choke" because it has no air.
Just my suggestion because it worked for me

 

Yes you can get a CEL from a vaccum leak, if not i can tell you if you have a vaccum leak from data block 32 in the ECM.
Other than that Lawnferie hit the nail on the head, 1.8T engines commonly get carbon build up on the throttle body valve which can cause an excessing amount of air entering the engine at idle messing with the engine management.