My problem with my '86 240dl (123,000) Is that on occasion when I give the car gas I get no power. This happens in the 30-40 mph range, but doesn't happen every time I drive. I hear a "low exhaust note" noise coming from left side of the engine compartment. It almost feels as if it is "bogging down". It is especially bad going up hills and/or trying to pass in traffic. It seems to help if I pull over and turn the car off for a minute and then go about it. I'm not sure if this is related, but there is also and exhaust "rattle" at different times. I need to take the car in to get it looked at, but haven't the time or $$. Thought I could ask you guys first, and imput would be appreciated. Thanks.

My 2 cents, could it be catalytic converter, I'm not sure if the "low exhaust note" is backpressure? Related to exhaust rattle?