Wanted to know whats going on with my truck.

Hi wanted to know whats going on with my truck, got a fresh air intake on this and the air filter is cleaned and oiled. When I am accelerating ive noticed the rpms are going way to high. They are way higher than they used to be. Im concerned and a friend told me to check transmission fluid level and it was a little low, its still doing this although its not as high rpms as before adding fluid. Whats going on?