Help with measurement blocks for mass airflow sensor (MAF), lambda sensor

"Hi, could someone please explain to me how to measure the mass airflow sensor and the lambda sensor on a AJQ 1.8t engine, and specifically, how to do it while in 3rd gear, from 3000 RPM to 6000 RPM? My car has been running poorly for a while, and it seems like I'm experiencing power loss above 4000 RPM. I want to start figuring out what's causing the problem. The error memory isn't showing anything." Could someone please help me? Thanks in advance.