2nd Gear Engine stops between 4-5k rpm

[Focus_Rider]

Hello y'all I'm new here and just got my 1st ST. and love this thing. It is a 2019 Fiesta ST and when I got it it had some surging related issue, at the time was "rectified" by the Ford dealership I bought it from. Well, I've owned this vehicle for about 2 months, and the surging comes after fueling up. WELL today I had something unique happened. Just the other day I went on a roughly 100mile trip no issues. Today I noticed when in 2nd gear and doing a WOT pull or just cruising in 2 and between 4k-5k RPMS the engine. I guess suddenly stops accelerating. It won't die and if I try to push it, it will act like there's no boost, wont do much of anything. No MIL on at this time The moment I shift into 3rd all is fine. No issues in any gear but 2nd. The ONLY thing I have done differently was when I came back home from my trip, I added 4 gallons of mid-grade (mixed it with the high-grade fuel in the tank) I just wanted to get some opinions. I got that ford extended warranty 3yr/36k but with this being my only vehicle atm I kinda want to figure it out before I commit to dropping it off for a week at the dealership.

 

[Zeille]

what do your fuel trims look like? especially low side fuel pressure? i had an issue where this would happen at the most random times in 3rd gear, and it was my low side fuel pressure sensor. car would bog down, not accelerate, and not build ANY boost, then come back on like nothing happened. do you have a COBB accessport?