Ford: 1999 Ford Expedition Sputtering, octane booster, transmission issues

Question
I just got gas at a station I normally don’t purchase from and within 15 minutes or so, my truck started sputtering and sounded like missing some.  I have over 160k miles on it.  It doesn’t sputter when idling much at all and usually only does it when in 3rd or 4th gear.  I have it scheduled to run on a diagnostic next week but just wondered if this sounds more like bad gas, a bad fuel filter, a bad valve or filter of some sort or transmission issues? I have read many similar instances on the board and just want to ease my mind a little before I get it checked.  The wallet is a little tight these days.  Thanks, Jimmy

Answer
It sounds like bad gas.. (Or a little water in the gas...) you might try some octane booster or a product called "Dry gas" it will help get any moisture out of the fuel system..... it doesn'e sound major (Based on the fact that it happened right after filling up). let me know what happens at the diag...