Now you might think that spraying lighter gas roughly speaking a warm engine isnt wise, however the flash /ignition point of gas is nearly 400C consequently you compulsion a naked flare or spark to set it off and Ive used this method for many years without incident. fake your artifice through each attainable joint one at a times and you should find it. I use a slightly flattened fragment of brake pipe and some rubber hose from the can of lighter gas to present a spraying wand and permit a dispatch blast of gas into each area, especially those difficult to accomplish taking into account 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 not at your best pump will every result in insufficient fuel subconscious delivered to the engine. Might after that be worth cleaning out the idle rapidity rule motor / valve as these acquire clogged taking place subsequent to carbon and some brake cleaner washed through helps release things off.
have you looked into throttle body coking and/or combustion chamber/valve carbon buildup? are you going on to date on all maintenance; spark plugs fuel filter pcv vlave etc? have you performed a visual inspection and listened to engine as it warms going on and is warmed up? oftentimes in engine feint many factors may cause the similar symptom(s)