Check the hose clips for tightness and inspect the trunking for any cracks or splits and along with every the vacuum system, the small bore pipes and fittings for cracks and missing parts. The best pretension to locate a leak is to have the engine dispensation and hot and then spray lighter gas /propane or brake cleaner more or less each joint in turn. If the engine rev s taking place 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 sick pump will every result in insufficient fuel subconscious delivered to the engine. Might furthermore be worth cleaning out the idle readiness control motor / valve as these acquire clogged occurring in imitation of carbon and some brake cleaner washed through helps free things off.
have you looked into throttle body coking and/or combustion chamber/valve carbon buildup? are you taking place 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 up and is warmed up? oftentimes in engine affect many factors may cause the similar symptom(s)