Hi whatjigg -
Do you have a
ScanGauge? If not, before anything else, that's what I would recommend. Just going tank-to-tank offers little usable information in terms of feedback to your driving style.
If I were still in Ontario (1000 Islands), I'd offer to meet with you to do a driving clinic. But I'm on the east coast for the winter. I bet by the spring when I get back you'll have this sorted out!