I have a 1991 940 turbo and it has been a good car. Not totally probably free but has served us well. A problem just started where it bogs down when accelerating quickly or to the point where it needs to drop down into another gear to pick up speed initially. I can drive it normally w/o problems but when I am on a steep hill or have to pass someone and hit the gas a bit harder to pass or whatever, it bogs right down. Could this be the knock sensor? Thanks..brickboard has been a savior for me in the past.