Lowcummins

It will even do it in the stock tunes provide, the transmission bucks really bad. After Tune level 4

Hi, I have a stock 99 Cummins that has a intank lift pump(before I owned the truck) I recently put the iQuad on and when I created a tune, I can upload my tune if need be, but I would be about 13psi of boost then slowly give it throttle it will just jump up to about 25/27psi. The truck almost bucks, but once you pass that “surging” point it pulls very hard. What would make it jump psi so fast? And no I do not a have a fuel pressure gauge.