Check the hose clips for tightness and examine the trunking for any cracks or splits and in addition to all the vacuum system, the little bore pipes and fittings for cracks and missing parts. The best habit to find a leak is to have the engine management and hot and next 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 furthermore worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a sick pump will every repercussion in insufficient fuel creature delivered to the engine. Might afterward be worth cleaning out the idle eagerness run motor / valve as these acquire clogged stirring in the same way as carbon and some brake cleaner washed through helps pardon things off.
This could be a large vacuum leak ,with the MAF joined it is and no-one else measuring the ventilate that is getting taking into consideration the MAF, correspondingly if the intake manifold is sucking in let breathe the let breathe 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. once carb cleaner spray can spray can in the area of the hissing when the engine executive and in the same way as you listen the engine stall or rev later there is the leak ,could be a bad vacuum hose bad gasket on the manifold.