Check the hose clips for tightness and inspect the trunking for any cracks or splits and as a consequence all the vacuum system, the little bore pipes and fittings for cracks and missing parts. The best exaggeration to locate a leak is to have the engine handing out and hot and subsequently spray can lighter gas /propane or brake cleaner on the subject of each joint in turn. If the engine rev s stirring you ve found your leak.
Its as a consequence 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 repercussion in insufficient fuel brute delivered to the engine. Might along with be worth cleaning out the idle zeal manage motor / valve as these get clogged going on following carbon and some brake cleaner washed through helps forgive things off.
have you looked into throttle body coking and/or combustion chamber/valve carbon buildup? are you happening to date on every maintenance; spark plugs fuel filter pcv vlave etc? have you performed a visual inspection and listened to engine as it warms taking place and is warmed up? oftentimes in engine pretense many factors may cause the similar symptom(s)