Hi, Scotty!

I have a 2001 V6 auto Mustang. Since the day I bought it I’ve had a weird acceleration hesitation issue. The car will gradually accelerate without issue, but when merging on a highway or needing to pickup speed quickly it hesitates. It is much worse when under additional load from having my A/C running. I’ve replaced: Plugs, coil pack, plug wires, intake filter and fuel filter. I’ve also cleaned the MAF, throttle body, and IAC. It almost feels like a misfire but I’ve never had a code for that, only an Evap leak. My searching leads me to believe that I have a vacuum issue or fuel pump, any ideas?