Seems a bit strange that you didn’t have problems all summer before now. Was it hotter than usual?
Possible that you got a batch of winter fuel with a higher RVP? I believe the switch date is September 15. This has happened to me on hot days near the 6/1 and 9/15 transition dates having the high RVP fuel on hot days with a long engine run.
Knowing this, I work around it.