Lack of power help

[outlaw6oh]

I need help trying to diagnose a problem, my truck doesn't want to accelerate when stock, it runs fine at idle builds boost as accelerating but even though I'm floored the truck seems to just slowly pick up speed like I'm barely touching the throttle. I had a new stock tune sent to me and the same problem occurs with it, when the truck is tuned it seems normal although I'm sure this affects that too it's just not as noticeable. What could cause a problem such as this I'm out of warranty with my mods so I'd rather not take it in if at all possible any help would be greatly appreciated.

Thank you,Brian