Find out what the code is first.If the cruise control light is flashing as well then thats bad.I suggest buying a tactrix cable and downloading Enginuity to log with.Seriously,it's 10X faster to diagnose stuff if you can datalog the car.Even if you don't know what your looking at,other people do.You can just post the log.When you test for boost leaks you need access to an air compressor.This is how you test for boost leaks.It still has the stock air box. We checked all the piping from the turbo to the throttle body. Nothing was loose. Check engine light is on. Sometimes it has spells were it idles rough. The clutch is slipping but that should not be the problem. How could you test a air bypass valve (blow off valve).