I do things slightly differently. It sounded like his engine is beginning to get fouled plugs. Before starting, I go full throttle and full mixture and turn the fuel pump on 3 to 5 seconds and turn it off. I then pull mixture to idle cut off and throttle all the way back to idle. After, I check and make sure that my beacon is on, yell clear and I start slowly advancing the mixture as it catches only doing about halfway. Then I adjust my RPM to 1100 RPM for 30 seconds and monitor oil pressure. After I run it at 900-1000 rpm. It is a lot smoother on the engine. During run up I adjust mixture 1/8 inch in from highest rpm for takeoff. I keep CHT below 400. EGT isn’t so important.