Check the hose clips for tightness and inspect the trunking for any cracks or splits and along with all the vacuum system, the small bore pipes and fittings for cracks and missing parts. The best artifice to locate a leak is to have the engine admin and hot and after that spray lighter gas /propane or brake cleaner vis--vis each joint in turn. If the engine rev s going on you ve found your leak.
Might afterward be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can pull off a fast anomaly locate if you unplug the meter and direct the engine without it. if the engine condition is the thesame subsequently chances are the meter or the connection to it is faulty. Its then worth cleaning the MAF sensor wires, as they can get coated considering dirt beyond epoch which later offsets the reading. Use some contact cleaner or brake cleaner to spray onto the wires to surgically remove the dirt upon no account lie alongside the wires considering all as they are unquestionably fragile
I'm reviewing your question now, and will state help following your reply ASAP. Rgds Greg. What deformity codes pull off you have. Does the engine control later than the MAF disconnected. once the loud hissing unassailable this could be your problem. This could be a large vacuum leak ,with the MAF linked it is single-handedly measuring the ventilate that is getting following the MAF, so if the intake manifold is sucking in freshen the expose to fuel ratio will be entirely out and cause the engine to stal