I had the same hard shifting problem and it was a plugged vacuum line to the tranny. Seems to me I traced the line from the modulator--drivers side of tranny, green color thingie-- under the hood you'll find that the line from modulator fits into a "T". Thats where mine was plugged. Cleared it and the hard shift went away.

Try a search on "banjo fitting" or "banjo bolt". I have read somewhere this fitting can get stopped up causing lack of power. Lack of power would cause your lower fuel mileage. ALDA will probably need adjustment after cleaning the banjo fitting. Power should be smooth and you should not feel the turbo "kick".

Motor mounts are very common problem it seems and sounds to me like you need them. I bet it shakes harder when the a/c or defrost is running, right?

Welcome--I'm fairly new too and have found this site to be a great tool. GREAT job on th B2. Thats something I've read about here and no way would I attempt to dig that deep into the tranny. Haven't had the need--yet.

Cheers,

Bill