I was becoming very frustrated with my 91 240 sedan after testing just about everything the Bentley manual advised. I was not getting any acceleration, yet the motor started just fine and was ok at idle. I was convinced that it was stuck in limp mode, yet for no good reason. It seemed ok in first gear, but thereafter if I really pressed the pedal I would get this baaaaaaaaaaaaaaaa kind of sound and very little acceleration. That made me think that it was getting plenty of air but not enough fuel. A little bird told me to check the exhaust. I thought "now that's just silly, wishful thinking", yet this little bird has never let me down. I took my car to the local muffler guys. I asked them to work the exhaust over from the cat back, and just leave me with one new muffler at the rear and no resonator. He drove the car on the rack, climbed into the pit and within a minute said " hey guy, you need a cat, not a muffer". I told him to put in a new cat and replace the resonator with a straight pipe, even though I was not convinced that the problem would be solved, after all, I had never heard of a broken cat clogging a muffler system, but mind you, I had spent hours testing and cleaning various components. As I began to drive off I knew that I would feel either foolish or happy... I drove happy! tweet tweet...