this is an S4 TII, with no p/s

my car has a bizzarre idle problem; it idles anywhere between 1000 and 2500 rpm. It usually starts out low, and as i drive it gets higher. In addition, its begun to die when i start it lately (usually with warm starts). I start it, it revs up and then drops right down and dies. I can usually catch it with the throttle, rev it a couple times and it will be fine, but sometimes when I try to catch it is just stumbles around 500 rpm with the throttle to the floor.

This car has the original engine with 48,000 miles on it, so I would assume the compression is good. Its been doing the high idle thing for as long as I've owned it, about a year, but only recently have I had trouble starting it.

Any ideas? vacuum leak? TPS?

oh, and I blocked of the BAC and it didnt help, so i dont think it is that (although i guess it could be causing the starting problem)