Torqstorm.. let's see how it does

My guess is you are indeed running out of pump running E85
That pump is rated way less on E85 than gas.
I don’t like the magnafuel stuff myself, they are prone to leaking, often before they are very old, and they don’t like continuous duty much either( like on the street)
1st and 2nd are missing less than in high gear because the tranny is helping leverage your power.
At 1 to 1 she is working.
I would step up, and use another vendor.
That all said, I am saying this as a guy who had zero issues with a Holley black on a heavy 9 sec car( later swapped to a whole new bigger fuel system and zip on the slip)
So to me, fuel pumps are often overkill . In your case, probably not.