Have a 2000 ford ranger flex fuel 3.0l v6. Automatic Transmission just started slipping really hard last night. Seemed all of a sudden. Slips in 1st and reverse really hard barely drives. When you put it in 2 or 1 on shifter it drives pretty good. Fluid seemed really high but then sucked alot of it down after running it for awhile. Never checked fluid before so not sure if it's high. Engine leaks or burns 1qt oil in like a week recently since last month. Not sure if thats related if it was possible leaking out the rear main. Any info will help probably going to buy a tranny out a junk yard unless anyone thinks something else. Thanks.

 

Reads like one-way clutch(sprag) is failing or failed, its used in D and R, in 1 and 2 the Coast Clutch is used
Requires a full rebuild to repair a sprag

So doesn't read like a valve body, solenoid or wiring issue

2000 Ranger 3.0l, FF or gas only, has the 4R44E model automatic
Because its a 2000 you can use an automatic from a 1995 thru 2008 Ranger 3.0l or Mazda B3000 as a replacement
Must match 2WD or 4x4 but any year is fine to use
2001-2008 will have 2 extra external sensors(ISS, OSS) that you don't need/use, but that's fine, they are also called 5R44E, but same trans internally