air flow meter or idle control valve damaged running on gas

[gasboyjay]

I was running my e30 320i se (1989) on lpg, when then was quite a large backfire, causing the hose connected to the idle control valve and the throttle body to pop off (i presume this is supposed to happen as there is no hose clip to fasten the hose to the icv) but ever since the engine has run fine on gas, but when on petrol there are flat spots then sudden acceleration (though some days are better than others) and when idleing on petrol its droping rev then picking up again every second(dipping), hovering around 800 revs(but fine on gas) i have also noticed that the icv its BUZZING at me!!! can't be good, but i was convinced it was the airflow meter that is bent maybe its both what ja think? i know there aint going to be nobody with the same problem as me thats just my luck but if you got a theory please come forth cheers jay b

[Templ8e30]

The ICV is supposed to buzz.

As you say it soundslike the AFM flap is sticking.

Cheers,

Iain T