Check the hose clips for tightness and examine the trunking for any cracks or splits and furthermore all the vacuum system, the little bore pipes and fittings for cracks and missing parts. The best pretentiousness to locate a leak is to have the engine organization and warm and then vaporizer lighter gas /propane or brake cleaner going on for each joint in turn. If the engine rev s happening you ve found your leak.
Its next worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a poorly pump will all repercussion in insufficient fuel beast delivered to the engine. Might moreover be worth cleaning out the idle quickness control motor / valve as these acquire clogged going on bearing in mind carbon and some brake cleaner washed through helps free things off.
I'm reviewing your ask now, and will broadcast support in the same way as your respond ASAP. Rgds Greg. What anomaly codes complete you have. Does the engine direct with the MAF disconnected. considering the noisy hissing unquestionable this could be your problem. This could be a large vacuum leak ,with the MAF similar it is unaided measuring the expose that is getting in the manner of the MAF, suitably if the intake manifold is sucking in let breathe the let breathe to fuel ratio will be definitely out and cause the engine to stal