I think I may have an air leak.

[ah]

I checked all the usual places,but someone on here said under the throttle body area there's a rubber bung that sometimes falls out and causes rough running.Can someone give me a bit more info on it, exact location and a picture would handy many thanks.

[kam-325i]

never heard of that, but you could check the metal pipe that connects to the uderside of the inlet fanimold from the sump....if the seal (rubber O Ring seal) is knackerd, that would cause rough running....

[aimlessrock]

Pull off the inlet and inlet and inspect...then take from there mate.

[Brianmoooore]

The bung is blanking off the nipple where the vent pipe from the fuel tank would connect if your car had a cat. and other associated bits.
Six pot cars have a bung pushed over the nipple, but four pot cars have a length of hose attached, with a bung in the end of the hose.
The original rubber bung on all six pot E30s will have failed by now, and will either have dropped off completely, or just be a few tattered remains hanging on. It might have been replaced already, of course
The nipple and bung are on the underside of the throttle body, almost touching the throttle position switch.