Check the hose clips for tightness and examine the trunking for any cracks or splits and after that every the vacuum system, the small bore pipes and fittings for cracks and missing parts. The best showing off to locate a leak is to have the engine dealing out and warm and after that spray can lighter gas /propane or brake cleaner regarding each joint in turn. If the engine rev s going on you ve found your leak.
Might next be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can reach a quick aberration find if you unplug the meter and direct the engine without it. if the engine condition is the same then chances are the meter or the connection to it is faulty. Its in addition to worth cleaning the MAF sensor wires, as they can get coated past dirt more than mature which later offsets the reading. Use some entre cleaner or brake cleaner to spray can onto the wires to remove the dirt on no account be next to the wires taking into consideration anything as they are utterly fragile
have you looked into throttle body coking and/or combustion chamber/valve carbon buildup? are you going on 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 happening and is warmed up? oftentimes in engine statute many factors may cause the same symptom(s)