98 Saturn SL2 Twin CAM 145k miles

About 2 weeks ago I started the car and let it run for about 20 mins to warm up. I put it in reverse and it wouldnt go anywhere. I then put it in drive and it would not shift out of first gear. RPMs would just rev up real high. I took it back home ASAP. I checked everything I could. I let it sit for about an hour to go call around for mechanics. I found one, I got back in the car and it drove perfectly normal to the shop after it cooled down. They ran diagnostics and got 7 codes. 5 of them had to do with the RPMs running to high. While trying to shift I assume it was when it would not shift out of first. Another one was a temprature code and the last was some kind of sensor code. Service engine soon light also came on. Past to weeks it has ran fine. Until tonight. It would shift really hard but after 2nd gear it would bog down and would not speed up. When it is cold it seems to work ok but if I let it warm up it would not run right. What could be causing this? I have read similar questions but thats just it. They are just similar. Please help us. It is our only car and we are thinking of getting a second saturn 99 model. Would we expect the same problems with the 99? Could it be a clogged filter? I am sorry this is so long but me and my wife share this car and I wanted to make sure I explained clearly. Thank you soo much for having this site. You Rawk!