Lack of Power When Running at Constant Speed (problem is difficult to describe)

[s240west]

My problem is difficult to describe. My 92 240 is stock (except for a Magnaflow performance muffler), has 130k miles and has newer plugs, wires, etc. It's also an automatic. Here's the problem - when I'm running at a constant speed, periodically the car seems to totally lack acceleration when I press on the gas (RPMs change a little, but not much). It seems like the timing isn't advancing or something. When I let off the gas, it seems to reset and I can accelerate again. The problem doesn't happen a lot, just sometimes. Generally happens when it's in third or forth gear.

Any help would be greatly appreciated. Don't think this matters, but the car is a convertible.

[jerdog1]

How many miles??? It sounds like ur automatic transmission is on vacation! Time for a rebuild! The lack of power is because its in the wrong gear!Good luck!

[onosqv]

you should pay attention to the actual rpms & speed (to figure out which gear) you are going & how much you are gassing the car (i.e. 20% throttle, 40% throttle, 100%, etc). Automatic trannies don't always downshift.

Having that info will at least be able to help you narrow down & perhaps consistently reproduce your problems. From there, FSM is your friend.