EGR valve and gas mileage

[impala67]

i decided i should not mess with my EGR. we have had "warm" degrees- thats 30F or so in our climate.... and i am getting huge mileage; atleast its couple miles better than in earlier regular measurements.
i got now last month (no boasting; this is fact) 10.4 liters on 100km in regular roads-daycare-groceries, quite same circles but no downtown city driving. while in coldest (0F- to -20F) winter I never reached 20MPG.

i drove like 233mi with 38 litres and thats appr. 23MPG if i calculate right. and bfg spiketires has been whole winter the same, same as original size and I fill it up in same station with premium 5% ethanol fuel full. And while listening the engine its not running 100% perfect, goes ok, idling so and so ok , but not as new (165k in odo).
ten smileys! i l respect my 3800 non-supercharged.