so if the summer fuel change over isnt til june theres a good chance i have winter mix in my tank. Very helpful. Thank you.If you aren't in any danger of needing this truck for a daily driver, wait through the winter and see if it quits. Allegedly, gas formulas change and the colder weather will knock stagnant heat down quickly. See if it quits then.
Not sure what you mean about winter gas formulations and stagnant heat, but with the switch to winter gas, they blend in even more butane (the largest contributor to vapor lock) since temps are cooler they can get away with it. (Butane is plentiful and inexpensive.) So on an exceptionally warm winter day with winter gas, you have the same problem. It's REALLY bad when you have a full tank of winter gas when summer comes around. Some blends (depending on what state and county you buy gas) of winter gas will boil at as low as 100°F. If it's a cold day, no problem, but if it gets too warm out, well you know.
Generally speaking, large hot cities with pollution problems require gas with higher REID vapor pressure values. This is EPA controlled and it cuts down on your gasoline vapors that leak out and contribute to smog. So if you are outside the city limits, sometimes buying gas in the city will help your problems with vapor lock/percolation. Here is a chart for summer gas, I'm sure you can find winter gas chart if you look. Lower numbers basically mean it wont boil as easy.