overheating issues

we just got my girlfriends car (88 buick regal .. 2.8L) back from her ex ... when we did it wouldnt start for anything .. so i replaced the fuel pump .. bam it worked awesome .. it had a huge problem with leaks so .. i checked all the fluids .. there was bareyl any oil, water, or tranny fluid .. i flushed them went ahead and refilled everything and started from scratch .. well it runs .. but it leaks like crazy i put some stop leak crap in the oil because i couldnt afford to try to replace all the seals yet and it pretty much stopped it .. it went from leaking over a quart a day to a quart a week .. so improvement .. it still leaks a little tranny but not near as much .. and i thought it was holding water but yesterday the thing died in the middle of a busy intersection .. she got it to run again by pushing it then it started then when die if she put it into gear .. so she would rev it up and throw it into gear and go for about 50 ft before it woudl die again and she said that when it died the first time it started to steam and hiss at her ...

when i got home i checked the oil first .. a little low .. added some then the water .. empty .. so i took the radiator cap off .. filled it and then went to start it .. wouldtn start .. dead battery .. so i jumped it .. fired right up .. sat there with the heater on .. checked the tranny .. fine .. turned the car off dumped about a gallon of liquid .. let car cool .. did it again this time ran for 5 .. didnt leak .. ran for anohter 15 didnt leak .. drove it hard for 15 miles .. ran so great not like it used to .. came home .. didnt spill any water ..

today she drives it to work .. dies in an intersection .. starts fine gets to work checks water and bam the reserve is completely empty .. but its not leaking when she put it in park .. any ideas??

where do i begin?