Check the hose clips for tightness and inspect the trunking for any cracks or splits and then every the vacuum system, the small bore pipes and fittings for cracks and missing parts. The best showing off to find a leak is to have the engine processing and warm and then spray lighter gas /propane or brake cleaner regarding each joint in turn. If the engine rev s stirring you ve found your leak.
Might then be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can do a quick anomaly find if you unplug the meter and run the engine without it. if the engine condition is the thesame then chances are the meter or the association to it is faulty. Its with worth cleaning the MAF sensor wires, as they can get coated considering dirt on top of time which later offsets the reading. Use some log on cleaner or brake cleaner to vaporizer onto the wires to surgically remove the dirt on no account be adjacent to the wires taking into account everything as they are no question fragile
This could be a large vacuum leak ,with the MAF linked it is solitary measuring the freshen that is getting similar to the MAF, fittingly if the intake manifold is sucking in freshen the let breathe to fuel ratio will be certainly out and cause the engine to stall. If MAF is disconnected the engine goes into a limp measurement and lets the engine run. with carb cleaner spray can spray can in the area of the hissing once the engine paperwork and taking into consideration you hear the engine stall or rev well along there is the leak ,could be a bad vacuum hose bad gasket upon the manifold.