BMW Repair: bmw 325i idle speed, e46 saloon, mass airflow sensor

Question
i own a BMW 325i e46 saloon the car has done 53,000 miles with full service history,about 4 months ago after using the car for a 90 km journey and resting for 10 minutes i tried to start the car,the car started but the revs where very erratic going to 11,000 then dropping to 3,000 back to 11,000 then dropping again,
the car leveled the revs at 6-7000 rpm but when i pressed the accelerator the car stopped running,
i then restarted the car and the same thing happened again there is no warning lights on the dashboard and this as happened 4-5 times now,most of the time the car runs fine its just the odd times which are getting more frequent
have you any idea what could be causing it
yours Paul from the UK

Answer
Paul, sounds like a faulty throttle assembly. Also could be a Mass Airflow Sensor. Could also be an idle valve buy those usually cause a no start. You didn't mention what year your car is. Have the faults read out by the dealer. Also the intake boot that goes to the throttle (under the intake manifold)cracks on the little offshute to the idle valve. If you don't have any faults then check the boot and remove the idle valve and clean with solvent so you can hear the door moving when you twist it rapidly in your hand. Also clean the throttle body if you are not going to replace it. Replace the gasket.
-Evan