I found this is not easy when your at speed. I tried to get a reading at 40 miles per hour for better accuracy. I picked the same 1/4 mile stretch of road and took a average both ways.

Idle a 163 degrees was 832 rpm. I could not get a 190/193 degree reading as the engine would shut off. I held the brake twice and it would start then shut right off.

Cruise at 40 miles per hour = 1300 rpm

Cold start, engine rev to 1535 rpm at 50 degrees outside temperature.