this problem in my 96 850r just started yesterday. under really light acceleration like around town the engine boggs under 3-5lbs of boost then all of a sudden goes into normal everyday power. this is also happening on the highway under really light acceleration at about 70 the engine started to bogg and shake. this does not happen at all under normal/ heavy acceleration, the turbo spools up fine and the car accelerates fine. this really concerns me, any help would be great.

 

Check engine light on?