any codes? please post at least one representative datalog for forum members to analyze. or load it up on a spreadsheet site on the web and post a link here.
common issues include c clips coming loose on the wastegates as well as the diaphragm tearing in the blowoff valves. also hoses coming off the solenoid atop the manifod.
doesn't hurt to make sure the tps, the IAT and MAP sensors are clean, and that the intercooler is not gunked up.