I have been stuck with this problem for over a month now. I have an 06 STi (pretty much bone stock). I installed a short ram intake 2 weeks before this happened. One day I randomly start the car and I have no power whatsoever and idle is a bit rough. When I press the throttle I can hear a "burping" or backfiring sort of sound from the intake. The engine has a strong hesitation and I have troubles reving it past 3000rpm. I have no CEL and nothing had come up in the past. I took off my entire intake system including the turbo inlet and all the hoses are fine. Inspected the inter cooler as well.
I replaced the MAF with a known working one and no difference.
I put the stock air box on and reset the ecu and still no luck.