The other day on the DC Beltway, I heard a "poof" sound then a loud rumbling sound that was kind of high pitched. I was going to pull off of the road so I put the clutch in. The sound immediately stopped. I decided to continue. About ten miles later I heard it again. I pulled off onto Rte 1 and heard it again, but not as high pitched (speed related?). Did not happen again.

Until this morning. Once again, the noise went away once I pushed the clutch in.

Any ideas? I just spent $4K on various issues on my '96 A4 quattro (5 spd obvously).

Any help would be appreciated.