a leak can cause all kinds of strange things.. it's definitely possible for a leak to cause your issues, i've seen it before.. you can still hit full boost even with a leak sometimes as well.

 

With a little ass turbo that spools full boost at less than three grand what makes you think it wouldn't make full boost if you have a small leak??

Check your vacuum hoses, biggest one I would think to check is the FPR line. If the regulator isn't getting what it wants fuel will be all screwy.

Better yet pull one off and see what it does so you are firmiliar with it, just don't pull the one to your Fuel Pressure Regulator unless you are careful.

 

use NGK plugs bpr6es is the serial number