Check the hose clips for tightness and examine the trunking for any cracks or splits and then every the vacuum system, the little bore pipes and fittings for cracks and missing parts. The best way to find a leak is to have the engine government and hot and subsequently spray can lighter gas /propane or brake cleaner approximately each joint in turn. If the engine rev s taking place you ve found your leak.
Its afterward worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a not at your best pump will every consequences in insufficient fuel being delivered to the engine. Might then be worth cleaning out the idle rapidity run motor / valve as these acquire clogged occurring past carbon and some brake cleaner washed through helps free things off.
This could be a large vacuum leak ,with the MAF united it is solitary measuring the ventilate that is getting like the MAF, fittingly if the intake manifold is sucking in ventilate the expose to fuel ratio will be completely out and cause the engine to stall. If MAF is disconnected the engine goes into a limp measurement and lets the engine run. subsequently carb cleaner vaporizer spray can in the area of the hissing following the engine presidency and as soon as you hear the engine stall or rev progressive there is the leak ,could be a bad vacuum hose bad gasket upon the manifold.