Ok, so heres the story, I got a Automatic 95 4 wheel drive Explo. w/ around 127,000 miles on it. The other day the Overdrive off light starts flashing and the transmission shifts really rough when I'm coming to a stop. I don't have a factory manual, so I couldn't figure out exactly what it means... So I changed the transmission fluid and filter. I have a Chiltons manual and it says to refill w/ 4 quarts or 6 quarts if you drained the torque converter too. Anyways, like 7 quarts drained out of the transmission pan (enough to nearly fill my 8 quart fluid pan). So I cleaned the transmission oil pan extremely good with GUNK solvent (was told by NAPA it was safe), put the pan back on, and then filled it with 4 quarts of Mercon ATF fluid (as told to in the Chiltons manual). I put it in park and let it idle for a little then checked the level, It didn't come close to where it was supposed to be on the dipstick, so I put in 2 more quarts. So it runs junky for a day or two, I read somewhere on the net about somebody washing their engine really good and getting rid of the problem, so I do that... Nothing...disconnect the battery, nothing... then the today the light goes away. All seems fine for about 2 hours. Then I try to back up, and the car slams to a stop like I hit something. So I go forward and it runs funny and I can hear clunks. So I stopped and pulled in to a parking lot to check the level on the dipstick. I take it out, clean it, put it back in, 3 times, the fluid is all over the dipstick, so I cant tell whats going on. Then I try to leave, and the car won't go in reverse. Also it won't go in neutral, it just stays in park unless you put it in drive forward . So I drove home, with minimal problems in drive. Then I tried reverse at my house and it sort of went into it, but then just started making a scratching/schreeching noise. So I put it back in drive and pulled into my spot and parked. So I have two questions,

1. how much fluid is supposed to go in the transmission pan?
2. Does anyone know (or think they know) what the problem is?

Sorry this is so long, I just figured that if I described everything in detail I would get better responses.