03 expedition o/d slipping?

[03ebexpy]

i recently went from southern california to arizona and noticed when in overdrive during acceleration it feels as if it's slipping but the rpm's don't go up. tranny fluid level is fine and after an hour or two of driving it's fine. ideas on what might be happening?

 

[tmajikman]

I would get a filter and a trans flush first and see if that cures you problems, the sooner the better bud.