smoothop

hello. i have a 95 classic sti

i have a strange problem. iv im reving it alittle like taking it to 5k rpm every now and then it seems to dump the boost. the gauge gopes crazy for a while flickers like crazy and sorts it self out.

somthing else that i think its related. even in low revs if im traveliong at say 70mph steady every now and then i feel a power drop. like some one is slightly pressing on the braks and then realeasing.

any ideas wheat this could be ?

possible leak i have checked all hoses that i thought it could be. all seem ok

thanks