Troubles like you've described can be the result of multiple issues acting in concert. That is, you've probably had a few small issues that alone could not cause the problem you experienced, but adding one more little problem may have connected a series of small issues putting the whole thing into the critical range. You may be fixing the small issues, but maybe not the right ones. I know that's not perticularly helpful, but it's just a thought.

If you suspect gas in the fuel, simply add some HEET or drain the tank and replace the fuel with some from a different, well-respected fuel station. It's a sad fact for us all that may gas stations have leaky underground storage tanks that both leak gas into the soil and groundwater, as well as allow water into the fuel.

Alternatively, try that earlier suggestion where you disconnect the supply side of the fuel pump and run a supplementary hose to a can of gas. If the problem only occurs when the car has been driving, chock the front wheels and put the rear wheels up on jackstands and let her run until the issue appears and you can see exactly what is happening.

Good luck.