nebraska03gt

So recentely I've noticed my car running really rich after I did a seafoam treatment (not sure if thats just what got me to realize it or not..but thats beside the point). I have an XCal3 tuner and went into the options for the tune yesterday because i remember seeing something about air/fuel %. I checked it out and all i can change on it was to make it run richer does anyone know how I can make my car run leaner without having to go to a dyno/tuning place?

Its an '03 GT...not sure if it matters what mods i got or not.


Thanks!