Vacuum advance tuning to maximize cruise MPG?

Great thread,,Has anyone had or noticed a surge at cruise while dialing in max vac advance?
Just asking as I swapped out a lean burn for factory electronic ignition. Factory spec was 16 degrees initial and at cruise say 45-60 it was surging.Took some initial timing out about 8 degrees,ok for now but need to get back into it and dial it in correct.
I hear ya,, gas went up 55 cents in 8 days here.