I just put my new engine in. Now my tranny is slipping. It came out with the engine and was removed and installed twice. I think I put too much fluid in there, would that cause slipping? Its a stock a4. It ran well before the pull.

 

Over filling the tranny has been known to cause slipping, even after the extra fluid has been removed. Trannys run off of pressure and there are a lot of pressure sensitive parts, by having too much fluid you add a lot more pressure and that can cause damage quickly.

When installing a tranny it is always better to put in a little less then what is required, run it for a few seconds, then top it off using the dipstick...