[Dean]

Sounds more like a tuning issue than a gas issue.

What mods and tune are you running?

What is the starting modifier in the tune after reset?

Also, if you reset after each fill, you lose all the other learning especially A/F trims which can easily induce knocking which will dump timing. Never ever drive hard after a reset unless you have a custom tune which has been very closely mapped A/F tables.

Think about how you drove during each period and the weather. If you drove hard right after a reset, the ECU is going to pull timing and be reluctant to re add it.

At this altitude, a good tune should run at 1.0 and stay there even on CA 91, maybe even 89 or 87.

Have you done any other logging to see what is happening, or are you just going by the multiplier? It is a really bad indicator of much of anything without any other data.