My 2.3t aut 9-5 99 chokes off on start up... recently since its been getting cold, used to do it in the really hot days also. Its got 123000 on it. I was thinking fuel filter maybe? I just changed the plugs so I know those are fine. The fuel filter is an original I think.... Also if i'm idling and I turn on my a/c as the compressor cuts on the car will shudder/choke out almost then rev back up to normal idle. Any ideas? Some cold days the car will idle high at around 1000 rpm or above a little on start up, idk if thats normal or not. TB has been replaced.