YS 140 FZ regulator question

[Legend5rc at aol.com]

Just finished a rebuild of my 140 FZ.  High end seems fine.  But the engine slowly dies WITHOUT an rpm increase at low throttle leading me to believe that the regulator is too rich.  With canopy off, I am able to pinch the fuel line and then it will run for a short time before it gets that rpm increase.  I did eyeball the regulator flush with the surface during re-assembly, but I should have laid a strait edge across the surface to be sure.  I have since turned in the regulator a half a turn and it is getting better, but not as quickly as I would have expected.  My question is, if the regulator was so far off to begin with, wouldn't the engine not have run at all?  Is there something else wrong?  Don't want to damage the motor, but so far everything seems OK and I will continue to turn that regulator in until she runs right.  FYI, keep in mind I live at 5800 ft so my settings are different from any low altitude folks.  Thanks.

Mike Cohen