2000 SL2 Acceleration Problem

Hi,

I have a 2000 Saturn SL-2, automatic transmission, and 30,000 miles on
it. It has been relatively trouble-free until the past two weeks.

The Service Engine Soon light came on recently and I was unable to
accelerate smoothly, especially while going uphill. Took it to the Saturn
dealer and they said something about the oxygen sensor being out of whack
and replaced it. Now the SES light is off. It ran OK for about a week but
now I am having problems driving uphill again. It seems to take a long
time to accelerate, also the shifting is really rough. When it goes from
2nd to 3rd its like a swift kick in the pants. The tachometer is at
4000-4100 before it shifts which seems high to me. Also, when I am going up
hill and the car is really straining and shaking, the SES light starts
flashing. I know from the owners manual that this means it is mis-firing
somehow.

I checked the oil level and the transmission fluid level and they are
both normal. Also, no leaks underneath the car. No warning lights coming
on other than the SES flashing when I go uphill.

I am thinking that something is wrong with the transmission. I don't
know that much about automatic transmissions, not even sure if they have a
clutch

Has anyone experienced this type of problem before? Any ideas on the
cause of the problem?


JD