I need Help, My Buick wont shift right

OK I'm not goingo to lie to anyone here I'm not a genius when it comes to cars, but I'm not that dumb either. This is my problem, a couple of months ago during the winter I got stuck in the snow, I did the dumb teenager thing and kept putting it into drive reving the engine, then putting it in reverse reving the engine, etc.. I finally got out and the next day my car started to over-heat to the point where I had to keep pulling over and putting snow on the engine.. (I know it was dumb) Well, it finally started dying on me and I would have to restart it and try getting home. I finally got it home and realized my water pump was done so I replaced it, and then I realized I cracked my radiator, so I replaced that, after I filled the radiator and resevoir with coolant, it actually started running pretty good, then here lately it started trying to overheat (it starts to climb realllyyy slowly) so I pull over and fill it with the water that I keep in my car, but the problem is when this happens the car is not wanting to shift, after I put the water in it, its fine for a couple of days. It's an old car with almost 200k miles, it has a V6 3.3 L in it, I know its about done but I just want to get it fixed so I can trade it in.. hopefully I gave enough information.. Any help would be great thanks.!!

Welcome to AF!!

First thing you need to do is to see where the coolant is going. Check the oil to make sure it isn't a bad lower intake gasket. If not then check the drain at the heater core. Sometime this will leak and you won't see the water leaking. Once you find the leak and fix that I think the tranny issues will go away. Since the radiator also provides cooling for the transmission, when you are low on water the tranny overheats just like the engine. One way to prevent this would be to install an aux. transmission cooler. This will help to prevent the tranny from overheating on you.

Ok I think I figured out the problem.. when I changed the radiator, the trans. line was so old it broke off, so I mcGyvered it and took a piece of pipe and connected two pieces of rubber piping and o-ringed it together.. so it went.... Rubber Tubing(o-ring)Metalpipe(o-ring)Ruber tubing and it connected to the radiator, well one of the o-rings came loose so it was causing tranmission fluid to leak.. I still dont know if this will help with the Radiator, but I think it will fix the tranny... I still have to drive it around.. but I think that should have done it.. Thanks for your help