looping idle with a knock then......

a friend of mines 97 accord had a helix on it which is now off the car. the car still loops and when it does it has a knocking noise that sounds like its something in the bell housing. however if you unplug the airflow sensor and plug it back in the looping is gone and it idles fine and even the knocking is no longer herd but when you do that no matter how much you rev the engine and ride the clutch it still tries to die unless you turn the car off and start it back then the looping and the knock comes back. it still runs strong but what could be the problem ???????

Did you ever fix the problem

no not yet we have a friend in the military thats coming home from over seas next week so we're getting his car ready for him when he gets back