I'm having some issues with the Transmission on my 1993 Chrysler Concorde 3.5l.?

The problem when i got it is that the transmission leaks slowly so i top it off every now and then, it idles high though not since my more serious problem has arisen. A couple of days ago when i was in rush hour traffic, when id stop at a light, it would idle fine, then it would suddenly die, and start right back up on its own. and it would repeat after i accelerate from the light a few feet. When I'm going full speed it will jerk a little bit intermittently and the rpm meter would go down then back to normal, even though I've got adequate fluid levels in all areas. I recently had the starter looked at because the battery died after i left the keys in it half turned over night, and got a new battery and it wouldn't start. mechanic said it was that the starter was jammed, and it started right up after coming off of the wrecker. I know many people would say to get a new car, but i didn't qualify for the cash for clunker deal, and I'm only 19 and cant afford a new car. I need some serious advice here please! The mechanic also said that the computers on chryslers die when the battery is dead for a period of time, and it would need to be driven for 30 mins to reset, but i drove it more than that, and this problem persists, and is very stressful, especially in rush hour traffic, but when i get out to the country where i live the stress leaves. I dont want to break down in the middle of the hood one day. and any advice would be appreciated.