'97 F250 5spd with 193k on her, 6637, full 4" cough 7" stack cough, edge evo lvl 1- I drove up to the green bay area last weekend (about 200miles each way) and I couldn't help but notice that after driving at a steady 70mph for a while, if I go to pass someone or even speed up, the truck stumbles pretty bad. If I ease into it lightly, it will go, but stomp on it at all and she doesn't move. I'm thinking it may be time to do the injectors. It smokes a lil bit on cold starts too- injectors? Also the last time I turned the prgrammer to level 3 it seems to have less power, the thing misses like crazy if I romp on it. Level 1 works fine for around town at least. thanks for the help

 

any trouble lights?

I'd look at fuel pressures. Fords specs is about 55psi. The OBS system barely supply's that stock. If the pumps weak or even the filters cloged it will hinder performance. The computer on both the OBS and SD does NOT monitor fuel pressure. Its a cheap thing to check. I run an electronic fuel pressure gauge just to keep an eye on it.

 

I would bet on the programmer first. I have heard of them getting weak every now and then so you may have to reprogram it.
Try removing the programmer and programs and see what that does.