Guys I need help from you, I am experiencing what I believe to be a drivetrain problem but not sure if it's the tranny or tc...Here's my symptoms that only happen in a cruising de-acceleration mode. At about 50-60MPH while de-acceleration (foot off gas, no brake & in overdrive) I can feel the car trying to go backwards (like a quick stiff brake) this only happens for a second, then as it coasts towards the 40-47 MPH it gets more of a jerking backwards feel that lasts a little more then a second or two and I can also observe my tach dropping 300-500RPM (500RPM drop is causing a much more severe jerking feel), these RPM drops are lasting only as I feel the jerking backwards and then the RPM's go back up when it stops jerking. The jerking backwards feel is only on de-accel and for the first time this afternoon I had RPM's dropping only 200RPM's then back up at a complete stop and idle situation...I have no ill-effects on acceleration...So I've kind of ruled out a motor issue... I'm used to the LT1 & LT4 vette's - so this C5 setup is a little different and I'm not up to speed on C5 drivetrain problems yet. The car is a 99 A4 w 2:73 gearing..car about 65,000 miles on it.. If anyone could chime in on this, I would be greatful. I have no codes showing a problem. It's almost feeling like the TC is bouncing in and out of lock mode...This is very odd and kind of difficult to troubleshoot... I definetly know something is wrong here I just need a little helo figuring it out...