My Truck has a 300 cylinder with an overdrive automatic in it.
It has shifting problems.
On the wide open roads like the highway or straight roads where the overdrive supposed to work it works right but when i head up around curvey or roads in the hills (paved mind U) it slips. It'll pop out of gear for a few seconds then slam into gear HARD when going up the hill or moving slow in town. And when going down a hill it downshifts like you would a manual. Now I've road in a many of trucks overdrive but it shouldn't hold back down a hill like that. It's like dragging something
Any Ideas????

 

Checked your fluid? Which tranny? AOD or E4OD?

 

Fluid level perfect, I changed the screen 2 weeks ago. And I always check it every weekend.
The bottom of the pan was the cleanest my dad and me ever seen. not metal chips or anything.

 

Every e4od I have ever had that I bought second hand has failed with in 2 week of fluid change. And I flush all line while at it. I started taking to trans shop and same thing.

But is it slipping or trying to shift?? The Shift position sensor on side of trans can make it seem to slip and banger in gears . Good luck