I have a 1989 Chevy Celebrity Wagon. It’s got 124,000 miles on it. When I accelerate it’s fine but when I try to maintain a constant speed it starts to act as if it’s loosing power then getting it back quickly over and over again until I press the accelerator for more speed then it stops but continues once I try to maintain a speed over 40 mph. What could cause this?
The torque converter clutch might be shuddering. The next time it does this while moving at a constant speed, slightly step on the brake pedal while maintaining that speed. If the vehicle stops doing this, that’s torque converter clutch shudder.
You might try a product from LubeGard called Shudder Stop. This is added to the transmission fluid to eliminate torque converter clutch shudder.
Okay, I will give this a try and see what happens. Thanks.