Now you might think that spraying lighter gas more or less a warm engine isnt wise, however the flash /ignition reduction of gas is practically 400C in view of that you need a naked flare or spark to set it off and Ive used this method for many years without incident. play-act your quirk through each possible joint one at a times and you should locate it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to give a spraying wand and allow a deal with blast of gas into each area, especially those hard to reach bearing in mind large implements.
Its furthermore worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a ill pump will all outcome in insufficient fuel being delivered to the engine. Might moreover be worth cleaning out the idle swiftness direct motor / valve as these get clogged up following carbon and some brake cleaner washed through helps forgive things off.
This could be a large vacuum leak ,with the MAF aligned it is lonesome measuring the ventilate that is getting past the MAF, suitably if the intake manifold is sucking in expose the expose to fuel ratio will be utterly 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 the same way as the engine admin and past you listen the engine stall or rev superior there is the leak ,could be a bad vacuum hose bad gasket on the manifold.