Check the hose clips for tightness and examine the trunking for any cracks or splits and next all the vacuum system, the little bore pipes and fittings for cracks and missing parts. The best pretentiousness to find a leak is to have the engine executive and hot and next spray lighter gas /propane or brake cleaner regarding each joint in turn. If the engine rev s in the works 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 not at your best pump will every upshot in insufficient fuel beast delivered to the engine. Might as a consequence be worth cleaning out the idle speed control motor / valve as these acquire clogged taking place when carbon and some brake cleaner washed through helps pardon things off.
This could be a large vacuum leak ,with the MAF amalgamated it is abandoned measuring the air that is getting past the MAF, therefore if the intake manifold is sucking in freshen the let breathe to fuel ratio will be entirely out and cause the engine to stall. If MAF is disconnected the engine goes into a limp measurement and lets the engine run. past carb cleaner spray can spray in the area of the hissing with the engine executive and in the same way as you listen the engine stall or rev well ahead there is the leak ,could be a bad vacuum hose bad gasket on the manifold.