This problem started very suddenly, like it was an electrical issue, and it doesn't seem like a mechanical issue...

The problem is that when it's in Drive, it'll shift up normally from 1 to 2, but then shifts up suddenly to overdrive or neutral or something, and won't catch the next gear until the revs hit almost redline... then it feels like its slipping or something, and I can only go a max of 45ish mph.

I changed the oil with Valvoline red jug, and with some Lucas. I swapped the valve body and switched the output speed sensor. I unhooked the battery to try to clear the computer. There were no check engine lights. I've been getting around, driving in the 2 position, a max speed 45ish @ 4000 rpms...

Also, when in drive, the transmission doesn't want to shift down until I come to a complete stop, then it'll start in first again instead of floating around in a high gear. If I stomp on it in drive, it'll hold 2nd gear for a while, but if i baby it, it'll shift up too soon...

Again I think its an electrical issue because I never felt slipping or anything in the higher gears.. i just drove to Vallejo from Sacramento a week before the problem. I went up hills just fine. When I changed the oil it was a dark pink, with a bunch of clutch dust on the magnets. No shiny metal chunks. So any ideas would be greatly appreciated. Thanks!

This is my 2nd transmission, from a wrecking yard. I installed it around 50k, and I'm at almost 80k mileage. The first time we thought the transmission was bad, it was because it was showing these same symptoms. but it turned out to be the output speed sensor... I changed that with this transmission, and that didn't do anything... so I need to know what sensors/factors are telling the transmission when to shift...