[A4] Stumbling at low RPMs

[Derek Pulvino]

Car is a 99-A4 w/V6.  

As of late noticing a stumbling/missing on acceleration at low rpms.  Usually notice it from about 500- to 1500-rpms when accelerating at part throttle.  Car idles fine and not getting any "check engine" light illuminations.  If on say 1st gear acceleration I keep the rpms up at 1200 to 1500 and slip the clutch a bit it doesn't happen, and never see it occurring during freeway cruising or otherwise. Also seems to have gotten worse with the warmer weather, but that may also just be a coincidence.

As I don't have a VAG-Com, haven't been able to check for fault codes.  Guessing that would be a good place to start, but otherwise, any other ideas?  Would almost seem like a vacuum leak, but not sure why it would only occur at low rpms.

derek