Check the hose clips for tightness and examine the trunking for any cracks or splits and furthermore every the vacuum system, the small bore pipes and fittings for cracks and missing parts. The best exaggeration to find a leak is to have the engine running and hot and later vaporizer lighter gas /propane or brake cleaner regarding each joint in turn. If the engine rev s occurring you ve found your leak.
Might as a consequence be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can reach a fast malfunction locate if you unplug the meter and manage the engine without it. if the engine condition is the same later chances are the meter or the relationship to it is faulty. Its moreover worth cleaning the MAF sensor wires, as they can acquire coated in the same way as dirt beyond time which next offsets the reading. Use some read cleaner or brake cleaner to vaporizer onto the wires to cut off the dirt on no account be adjacent to the wires when anything as they are entirely fragile
have you looked into throttle body coking and/or combustion chamber/valve carbon buildup? are you stirring 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 deed many factors may cause the same symptom(s)