2001 Toyota Camry Acceleration hesitation

When I try to accelerate, after stopping at a red light for example, sometimes, but not always, the car lurches from once to several times and will only stop if I let up the accelerator.

Same with climbing a hill, even without trying to accelerate. Overall, worse with the A.C. On.

The absolute worst is when resuming speed after being on cruise control. For example, even on a level road, if I'm cruising at 50, brake down to 45, then resume cruise control, the car almost shudders (lurches about twice a second) until it's back to 50 again.

This has been going on for several months. I just had the timing belt and water pump replaced; that made no difference whatsoever.

Interestingly enough, the lurching is minimized somewhat the harder I try to accelerate.

Thanks very much for your response.