when 1st start can rev freely until it comes back under 2000 then wont go above it, like its in limp mode.or starving for gas. have replaced plugs, distributer cap, throttle position sensor, water temp sensor.

what do i do to it

Mechanic replaced belts with water pump. Sound comes from inside air compressor.

drive train is at 3000 rpm from 70 mph and up is this normal