2003 Dodge Ram Throttle position on 5.7 HEMI

Driving at cruising speeds. When I go to accelerate gradually nothing happens. Until I push the pedal abtou 1/2 an inch then it will downshift 2 gears and accelerate rapidly til I let off. This only happens at speeds above 40mph. I cleaned the throttle body and checked my air filter to make sure it wasnt any of them. Also the spark plugs and wires are good also. Where is the throttle position located? Built into the Throttle body? Anyway to check it to see if it is that. Also what else could it be.