Strange Rpm drop

[nofear39427]

I didnt know weither or not if I should have posted this in the Performance or just post it here because its kinda both.

Last night I got off work and got into my car,started it up and headed home
after getting on the interstate I was running around 70-75mph the next thing I noticed is that the car started to hesitate a little like it was running out of gas then the rpms dropped and the car began to pick up speed really damn fast.It has never done this before.I called my dad and told him about it and he said it was probally my O/D in my transmission.Is there reasonable doubt to say that my O/D may not have been working properly and just started to auctually kick in? Give me some feed back.Thanks