Boost leak?

[wasaekhan]

sup guys... jus finished a fresh swap on my s14 with a blacktop s13, walbro fuel pump, z32 fuel filter, Precision Fmic, Rfl bov, aem tru boost custom three inch exhaust aem uego wideband, now initially when i got the car it was bucking nasty, but when i changed the spark plugs to ngk's bkr6e's it was amazing!!... over time i felt like it just lost power, wideband skips around from 15ish area to 16-17 or blank @ idle, also when building up boost it seems as if the turbo which by the way is a t28 bb from a s15, is gasping for air in increments gets to 7psi then skips around to lower numbers like 4.5, it sounds like its suckin air like a pump, today i regapped the spark plugs to .028 and its running a lot stronger and its building boost up to 9psi but same deal its still walloping air in increments also wideband @ idle for the most part is better around 15ish.... PLEASE HELP!!