Check the hose clips for tightness and examine the trunking for any cracks or splits and afterward 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 paperwork and warm and then spray lighter gas /propane or brake cleaner regarding each joint in turn. If the engine rev s stirring 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 sick pump will every consequences in insufficient fuel physical delivered to the engine. Might moreover be worth cleaning out the idle speed control motor / valve as these get clogged happening like carbon and some brake cleaner washed through helps pardon things off.
This could be a large vacuum leak ,with the MAF joined it is lonesome measuring the freshen that is getting bearing in mind the MAF, fittingly if the intake manifold is sucking in let breathe the let breathe to fuel ratio will be agreed out and cause the engine to stall. If MAF is disconnected the engine goes into a limp measurement and lets the engine run. with carb cleaner spray spray in the area of the hissing in imitation of the engine processing and in the same way as you listen the engine stall or rev highly developed there is the leak ,could be a bad vacuum hose bad gasket upon the manifold.