I would suggest a dyno tune and ECU reflash from a reputable tuning shop unless you are willing to invest in the time to learn to tune engine management yourself. A turbocharged Subaru engine needs an overly rich air/fuel ratio under high boost to act as additional cooling and a hedge against damaging detonation. It is possible to tune the engine yourself using a UTEC, XEDE, or standalone engine management, it's not for the fainthearted. You won't have the luxury of tuning with a wideband O² sensor like the real pros use and a standard cockpit-mounted air/fuel ratio gauge is useless for tuning a Subaru engine. An exhaust gas temperature gauge is too imprecise, also.

There are various vendors that can ship you a reflashed ECU on an exchange basis or a piggyback device that is usually plug-and-play. Each must be ordered with a fairly specific set of engine mods in mind - venture to far from these mods and the tuning map (boost, air/fuel ratio, and other variables) may not provide safe power. Engine management provided by mail order is normally tuned conservatively compared to a custom dyno tune, which is tailored to your specific engine and needs. I'm pretty sure that any of these reflash or piggyback devices will address the fuel cut without need for an additional device.

You didn't fill out your Location field so no one local to you can suggest a tuner that might be in your area.

--
0==WW==0
"…axles of evil…" - george w. bush