truck is doing weird things

[SHARPCURTIS]

Ok guys so i still use this truck as my daily driver. So it normally runs fine except for the shuttering at certain rpm's, so i brought it home and it sat for about 2 hours, i went to go back out with it and when i started it, it sounded like crap sounded like it was knocking pretty bad but no smoke at all. I let the truck sit for another hour and i went back out and started it and just took it down the road for a little test.The truck stumbled a little at low rpms but when i throttle into it it runs fine.So i decided to bring it to my mechanic and while i was driving it on the hwy at 70 i floored it and the son of a ***** took off like a rocket i was at 95 in seconds.Now keep in mind this truck is bone stock and has never felt like this since i owned it.From a dead stop i would punch it on dry pavement and it feels like it wants to break the tires loose.When i got to my mechanics i shut it off and then restarted it 10 min later to take for another test ride and the truck felt like it normally did..
what can cause this

[draaronr]

ficm problems or injectors dropping out likely.

[Dvldog458]

Any update?
Maybe the EGR valve is on its way out??