Check the hose clips for tightness and inspect the trunking for any cracks or splits and then all the vacuum system, the small bore pipes and fittings for cracks and missing parts. The best quirk to locate a leak is to have the engine running and hot and later spray lighter gas /propane or brake cleaner almost each joint in turn. If the engine rev s occurring you ve found your leak.
Might with be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can accomplish a quick deviation locate if you unplug the meter and run the engine without it. if the engine condition is the same next chances are the meter or the association to it is faulty. Its as a consequence worth cleaning the MAF sensor wires, as they can acquire coated taking into account dirt over epoch which later offsets the reading. Use some read cleaner or brake cleaner to spray onto the wires to remove the dirt upon no account be next to the wires later whatever as they are categorically fragile
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 occurring and is warmed up? oftentimes in engine be in many factors may cause the thesame symptom(s)