To add to this... I'm sure modern ECUs don't do this, but... my ECU actually enriched the fuel mixture a little bit when electrical loads were present - even if you were, for example, going uphill at 50. This would be 0.1 e.g 15.0 down to 14.9, and I think it was unintentional as well. Just something to think about
P.S. the Pulse widths from cold are just like mine (2.3 when warmed up, 4.8 when starting for the first few seconds, quickly dropping to about 3.4, then slowly towards 2.3).