Not sure how to explain this, but here goes.
Ive got a 2012 F150 Lariat. 6-cyl with EcoBoost.
When trying to excelerate at high speeds to pass someone on a freeway or get up a steep hill, and my truck goes into overdrive (or I assume thats what its doing)...
The engine light comes on, I lose power (the truck doesn't turn off) it just seems to drop down to a low gear and I'll I can do is coast until I get back down to about 5 miles an hour.
When I pull off to the side of the road, and get down to under 5 MPH, the engine light goes off, and I'm good to go.

What's going on? How can I fix this? I've looked at other threads, but can't find anything that I feel is this exact issue. Do I need to reset a computer? Is it bigger than that?

 

That is not what overdrive is. That is limp mode. You should be getting codes with the engine light, those should help diagnose the problem.

 

Yup, you've got to pull the codes, i'd guess some boost related problem.

 

The problem is that the engine light goes off, the moment that I slow down. Will the OBD tell me past codes?

 

You can go to most autoparts stores and pull codes for free. Go see what it says. If there is no code, but you know it's going to happen in the right conditions, they may let you borrow the reader if you leave a deposit, then go and try and get the light to come on, and read the codes, then return the reader.

I think it's pretty obvious that OP described two things. One, he stomps on the gas and the truck DOWNSHIFTS (there is no "overdrive") into a lower gear and the turbos kick in and he's hoping to accelerate past someone or go up a steep hill, but instead the truck goes into limp mode (second thing).

 

It's supposed to, although sometimes these trucks are stingy with the codes.

There has been a lot of discussion here about problems like this with the EB. Intercooler drilling, keeping PCV clean, some other stuff has been common answers. I don't pay too much attention personally since I have a V8.

 

I've been having the exact same issue and can not find the solution anywhere. Did you figure yours out?