Check all the vacuum piping - i.e. to the turbo, turbo control solenoid, the vacuum reservoir, etc etc. Look for perished/split pipes and loose connections. A momentary glitch in the vacuum system will cause it to go into "limp lettuce" mode. When its working OK, if the engine can accelerate briskly uphill at 70mph+ then its unlikely to be the MAF sensor despite what VR6 says :lol: But if you struggle to accelerate (a high speed) , then yes, it could be the MAF sensor. It may also be the throttle potentimeter.