Auto Transmission Question...

Please, if you're not experienced with cars and just want to act like you know something, don't answer....

My tranny, that I just got (The old one died) a year ago, is acting up.

:::: When my air conditioner is off, I do not have this problem whatsoever...

Let's see... Problem number one: Driving down the road--- the rpms jump up and down like someone's hitting my gas (cause my car takes off too) and letting go... then hitting it again.. and letting go.. all while my car is at a general speed.. no speeding up no slowing down.. I have to let the car gear back down to get it to stop.... then if I speed up it does it again.. Also, the tran will stop shifting, I'll gear all the way down and speed back up after I hear that gear down and it'll be fine, (still does the rpm thing though)

It only does this when the car is HOT... mid-day.. it does it bad.. I live in Alabama and the heat has been horrid here lately.. my baby isn't used to it...I drive about 20 - 30 miles to school 3 days a week.. and until the car heats up in the morning, its fine... but like today.. they hottest day so far, my tranny went out twice and I was scared to keep driving

When it rains and it's cool.. my car acts a lot better.. not completely right because the engine is stil hot.. but my tranny has never quit on me in the rain..

I've hear a lot of different things (valves, overdrive wacked out, sensors), maybe someone has had experience and I can fix this myself, but if not.. that's fine too.. I guess I'll have some mechanic tell me I need a new tran and I'll pay the 2 grand for a new one.. even though I only paid 4 grand for the car. I can't ever add mods to my car for the fact that I'm always fixing it.

Thanks Guys! And wow, haven't been here in a while... where'd everyone go?

ANY HELP GUYS?

Is the CEL on?

yea.. the CEL light is on... one guy ran the code, didn't know what it was...

well do you remember what the code was?

Knowing the code will be a big help in figuring out whether it's a tranny or engine problem. If you could find it that would make things easier. I've seen this problem before but i'm not going to make any guesses until i see what the code is.