Check the hose clips for tightness and inspect the trunking for any cracks or splits and furthermore all the vacuum system, the small bore pipes and fittings for cracks and missing parts. The best habit to locate a leak is to have the engine processing and warm and next vaporizer lighter gas /propane or brake cleaner re each joint in turn. If the engine rev s in the works you ve found your leak.
Its in addition to 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 upshot in insufficient fuel innate delivered to the engine. Might afterward be worth cleaning out the idle swiftness manage motor / valve as these get clogged stirring in the same way as carbon and some brake cleaner washed through helps pardon things off.
have you looked into throttle body coking and/or combustion chamber/valve carbon buildup? are you happening to date upon every maintenance; spark plugs fuel filter pcv vlave etc? have you performed a visual inspection and listened to engine as it warms occurring and is warmed up? oftentimes in engine exploit many factors may cause the similar symptom(s)