Check the hose clips for tightness and examine the trunking for any cracks or splits and in addition to all the vacuum system, the small bore pipes and fittings for cracks and missing parts. The best artifice to find a leak is to have the engine running and hot and later vaporizer lighter gas /propane or brake cleaner something like each joint in turn. If the engine rev s happening you ve found your leak.
Might moreover be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can get a quick malfunction locate if you unplug the meter and control the engine without it. if the engine condition is the similar after that chances are the meter or the relationship to it is faulty. Its moreover worth cleaning the MAF sensor wires, as they can acquire coated taking into consideration dirt on top of mature which next offsets the reading. Use some open cleaner or brake cleaner to spray onto the wires to cut off the dirt on no account touch the wires bearing in mind anything as they are completely fragile
I'm reviewing your question now, and will publish back later than your reply ASAP. Rgds Greg. What deviation codes complete you have. Does the engine govern once the MAF disconnected. once the loud hissing sealed this could be your problem. This could be a large vacuum leak ,with the MAF connected it is unaided measuring the let breathe that is getting following the MAF, so if the intake manifold is sucking in freshen the let breathe to fuel ratio will be utterly out and cause the engine to stal