Hard Clunk in 94 SL2

I have a 94 SL2 Automatic with 125,483 Mileage on it.

I would drive it around regularly temp was around mid 70's. As I was at a stop light for a while before it changed and when I stepped on the gas pedal, the car revs up but starts to slowly accelerate until it reaches to

30mphs and then it seems to catch a gear and then speeds up from there. Once I pulled in a parking lot, it sounded like the car was going to die out.

As I got out of the store about 10 mins later, I got in the car put it into reverse and an almost seems like hard clunk, CLUNKS, i've had this problem before but it got fixed awhile ago but now its back. The same thing happens when i press on the gas pedal it starts to accelerate slowly, then switches gear after it gets past 30 mph.

Also the Anti-Lock sensor keeps coming up and also when i'm in my garage and leaving the car idle my car starts to die down. The air bag sensor is blinking off and on and also my Traction control light is going on and off.

I check the Transmission fluid and deicded to flush it out and change the filter and Trans. Fluid., and all my fluids are alright. Is there somethign that's draining my battery?

My car has an alarm, but the remote control isn't working so its left to be on valet mode. I also have a deck, speakers, and amplifier.

I'm not sure if any of these has to do with the car dying down? I know never listen to the radio without the car being turned on.