Check the hose clips for tightness and examine the trunking for any cracks or splits and with every the vacuum system, the little bore pipes and fittings for cracks and missing parts. The best artifice to find a leak is to have the engine management and warm and subsequently spray lighter gas /propane or brake cleaner concerning each joint in turn. If the engine rev s happening 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 accomplish a quick defect locate if you unplug the meter and run the engine without it. if the engine condition is the similar later chances are the meter or the membership to it is faulty. Its with worth cleaning the MAF sensor wires, as they can get coated in the manner of dirt on top of epoch which later offsets the reading. Use some entrance cleaner or brake cleaner to spray can onto the wires to sever the dirt on no account be adjacent to the wires past whatever as they are no question fragile
This could be a large vacuum leak ,with the MAF linked it is lonely measuring the ventilate that is getting once the MAF, in view of that if the intake manifold is sucking in freshen the freshen 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. in the manner of carb cleaner spray vaporizer in the area of the hissing afterward the engine supervision and afterward you hear the engine stall or rev higher there is the leak ,could be a bad vacuum hose bad gasket upon the manifold.