Transmission Issues

i have a 99 rodeo 2wd 6 cyl. automatic. Yesterday morning the transmission starting slipping in just about every gear accelerating and decelerating. I got it back home and waited for a ride to the mechanic. When i took it in in the afternoon it ran like a charm with no slipping at all. What in the world could this be? Fluid levels appear fine, no leaks, it has 75 k miles and has had all scheduled maintenence. I have owned since 15k miles.

when was the last time you had it flushed?

Does the gear indicator on the dash line up with the one on the floor (put it is D and then slightly push up or pull back and watch the dash to see if it changes).

Sliping trannies in Isuzu's is commonly caused by: Dirty fluid or low fluid. Change the fluid every 30k and everything will be fine.

It should have been done at the 60k service. I just spoke to the tech who said he got it to slip again (after having to drive it awhile). He said that a lot of GM's and just about every Taurus does something similar (i actually have a company car Taurus that did just exactly the same thing) and that a flush and an additive can correct the problem. They are going to flush it and add the additive and we'll see.
I'm not sure about the gear shift - i had the car at the shop before i read your post.