Loss of power/acceleration
 

I just bought a 02 ext cab 4wd and when im accelerating then driving at a constant speed it drops the RPMs at about 1800rpms(depending on speed it will be higher at higher speeds) and it will stay there like it is stalling. I can press on the gas a little bit because i feel the loss of power and keep pressing on the gas and the rpms and speed will stay the same. So ill press it harder and the rpms will shoot way up! I have no idea but it is very irritating! Does it going up hills too. I put a new K&N hi flow air filter, changed oil, new fuel filter and Cam Position Sensor. It has a new battery and altenator and looks like new plug wires but i havent checked the plugs yet. Has 85,500 miles. No CEL and no codes.....Any ideas??

BUMP!