318 mystery problem, somewhat solved!

hm interesting. 15.1 at idle and 16.1 at cruise seems really, really lean to me but I'll see how it takes it. I'm guessing that I should keep raising the idle air/fuel ratio as I stand there till it starts pinging? I'm just worried about leaning out the cruise a/f too much as I don't want to hit the throttle and have it lean out too much and damage something.