98 Trans issue
It *might* just be an electronics issue...... Might try unplugging the 8 pin connector on the drivers side of the trans. ('bout halfway back, plugs straight down into trans. Can be fun to get to if you have a 4x4.....) With that unplugged, the trans will not have ANY automatic function. You will have to shift manually, and put it in the gear you want it in. You won't have O/D, or TCC either..... if it goes into the gear you tell it to, when you tell it to, its an electronic problem. If it still exhibits undesirable behavior....... rebuild time.
Mother****ing YESSSS! it was my shift lever linkage bushing. About 6 months ago the bushing broke on me while on the road. So I got under there and rigged it up with some metal wire I had sitting in the truck, worked perfect so I just completely forgot about it. Well eventually the wire came a bit loose and when I was on D I was actually kind of teetering between 2 and D so the trans was getting confused on what it wanted to be in especially when hitting bumps and such. If I put the shift lever right in between neutral and drive, it shifts ****ing great again! Gonna pick up a new bushing today!








Wouldn't hurt to check it while you are down there. It's at least easier to get to.