boost i think ?

well lads i have a 94 wrx and wen i give it boot it hesitates like its hitting a limiter or something and then goes a bit and then it starts jumping again especailly in 2nd 3rd and 4th. The boost gauge is reading to .5 fine and then from then on it hesitates up to .6 or so and then wont go higher its set to .8 but will only go there if you bring the revs up slowly. There is no engine light on or codes stored and i checked all boost piping and all seem okay any ideas would be great please