727 transmission - I'll try to describe my problem

318 engine, 3:55 gears brand new from Dr. Diff, 727 transmission.

When I accelerate real slow, first gear takes a long time to shift to second. ....then when it does, it slams into second. Very harsh.

If i accelerate harder, if shifts normal and great.

As I come to a stop, it down shifts from second to first very hard...

Any idea what these symptoms are caused by?

Thanks for any help in advance!

Jeff