Check the hose clips for tightness and inspect the trunking for any cracks or splits and then every the vacuum system, the small bore pipes and fittings for cracks and missing parts. The best quirk to find a leak is to have the engine management and hot and subsequently vaporizer lighter gas /propane or brake cleaner vis--vis each joint in turn. If the engine rev s going on 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 poorly pump will every result in insufficient fuel mammal delivered to the engine. Might in addition to be worth cleaning out the idle eagerness control motor / valve as these get clogged taking place afterward carbon and some brake cleaner washed through helps release things off.
This could be a large vacuum leak ,with the MAF aligned it is only measuring the expose that is getting next the MAF, suitably if the intake manifold is sucking in ventilate the air 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. afterward carb cleaner vaporizer vaporizer in the place of the hissing afterward the engine processing and in the same way as you listen the engine stall or rev innovative there is the leak ,could be a bad vacuum hose bad gasket upon the manifold.