I have noticed that the acceleration on my '98 4-cyl Camry can vary greatly. While applying the same gas, on virtually the same incline, I can get very different results. This all with just me in the car, so weight is not an issue. Sometimes, I won't even floor it, going up a hill, and it takes off like hell. Other times I will floor it on even ground and it accelerates like a school bus.

I'm assuming this could be attributed to different shifting in different situations (automatic transmission), but I'm not sure how to harness the power of these great accelerations so I can get them all the time. Otherwise, if it's something else, I'm wondering what's wrong.

It's much easier to get the transmission to downshift on a upgrade than on level ground. Pay attention to downshifting and use what throttle is necessary to get the power you want by instituting a downshift. 2.2L engines are not known for their power and rely alot on downshifts to get the car moving at a reasonable rate. Don't forget that you can manually downshift by releasing the O/D button at high speed or shift to 2nd gear at lower speed.

You mentioned downshifting to 2nd gear... Do you mean slipping the shifter into the "2" position? If so, is it safe (for the engine and transmission) to go between D and 2 while the car is moving and gas is pressed? Thanks!

I know it is safe to shift between D,2,L and N. I did it many times. But don't shift to R or P when you drive.

It is no problem as long as you are not going too fast. Don't do it on the highway. Keep 2nd gear for slower traffic.

Shifting on the move won't affect anything going between D,2,or L,as the computer won't let it shift if it's out of range for that gear.
Differences in acceleration could be due to the A/C being on(less power),or off(more power).