i would like to jump in here.
i have a similar problem where car is running but wont "go" when accelerating hard. it is worse when cold. NO CHECK ENGINE LIGHT.
i have spoken to different shops and they all say no " light -no codes " .i am sure it is the mas. how do i check it?
there was mention of " soft codes" . are they still there after batt. has been disconnected?

QUESTIONS? QUESTIONS?