CD - I would recommend just drain and fills, as opposed to flushes.
The flushes can dislodge deposits and cause slipping/leaks.  It's just
like an oil change really, pop the tranny pan drain bolt off, drain out
old, replace bolt/washer and add exactly how much was drained via the
dipstick tube (assuming the level was right to begin with).

My Maxima does some similar shifting when I'm going really slow - its
as though there isn't enough momemtum for smooth engagement...  almost
like the tranny has to play catch-up.. this always happens to me while
up-shifting, e.g. I'm accelerating very slowly, but then tap the
brakes, the tranny still decides to upshift and I get an abrubt shift.

Hope that helps,
Nirav

Something I've been meaning to ask, I bought both my 99 Sentra and 98
Altima used with about 100K miles on them. I have no idea about the
maintenance history. Their auto trannies seem to be fine. So, do I
change the fluid or just leave it at this point? I've red several
threads on how changing old fluid just may lead to the demise of the tranny.

Now, recently, I noticed that the Sentra sometimes does abrupt "dumps"
into 2nd (or maybe 3rd?) gear. I'd be cruising along very very slowly,
you could almost walk next to the car, and the gear change would thump
to the next gear. What kind of problem am I having?

Thanks.

CD