95 wrx wagon

Hi all, i am new to this site and it looks pretty rad. I own a 1995 import wrx wagon auto, had it for about a year. The problem is it has started to hold back under hard acceleration, almost like it is on the rev limiter. Any help would be greatly appreciated. Under normal driving it seems to be ok, gradual build up of speed, but when i accelerate harder i.e overtaking it holds back.
Thanks in advance, Steve.