my 03 tb is having idle problems. when a load is applied to the motor instead of idle ramping up it goes down. it doesnt die but does dip below 500. it will ramp up then go down if i sit there and just idle. if you watch rpm at idle it drops a couple hundred then jumps back to normal ive did the throttle body clean and relearn procedure. 160,000 miles. recent plugs and variable valve timing actuator. im leaning toward new throttle body. what do u think nation?