s13 fuel slosh problem at half tank

[240sxrb25]

i have a built neo rb25 in my s13 making around 400-450 hp range. stock gas tank with an intank bosch 044, -8 feed all the way and -6 return.

the problem is when i get to half a tank it leans out terribly when accelerating in a straight line. 1st, 2nd, 3rd, and sometimes 4th.

i have the pump exactly where the factory one was, almost touching the gas tank floor.

when i experience this, i got fill up with e85 and everytime its 8-9 gallons that i can get in it. everytime.

after that its perfect again.

im not a huge fan of fuel cells, but if i have to then i will.

i just dont understand why this happens in a straight line because the fuel should slosh to the rear where the pump is....

any recommendations? thanks