2nd to 3rd flare

hey folks-

lately i've been getting a little flare when i'm applying power, going uphill, and shifting from 2nd to 3rd gear in my 1992 svx equipped with a subaru reman. 4EAT with around 120k miles on it (the tranny.. 150k on the rest of the car)

i'll be accelerating up a hill, in second gear, and it'll go to shift to 3rd, but the rpms will shoot up by about 1500 to 2000 before 3rd gear catches..

is this a brake band issue? a TPS issue? a solenoid issue? a worn gear issue? will changing the tranny fluid be of any help? i realize that the answer is probably going to be "take it to someone who knows what the @($* they're talking about and ask THEM" but it'd be nice to have an idea what's going on..

-adam