boost leak would throw off the idle slightly...u wud...or shud feel the difference..

If u go to str8 to 10 psi with barely any effort= boostleak

If the boost is building normal and doesnt go past 10= a line is more than likely not connected...

or idk if u took your whole setup apart to do timing belt but maybe the turbo wasnt bolted back on completly...check for loose turbo to mani bolts