Truck is Sluggish/Choking between 45-60mph

[C4UC101969]

Today in the morning on my usual daily route to drop off my son in daycare, on straight flat road as i was getting to the 45mph mark it started to sputter, kind of holding back gasping for gas or air, so I let the gas pedal go let it slow down a bit and then again gradually speed up, it went past the 50mph mark without any sputtering or anything like that, it was normal once again. Then after slowing down and then speeding back up to the 45mph mark it began to sputter again and gasp for fuel or air, I let go off the gas let it roll for few seconds and then press the gas pedal and it goes once again past 45 without hesitation.

So on the way to and from my sons daycare it did that sluggish/choking on and off scenario.

I run on ethanol free fuel only with 91 octane, there was half a tank in the truck so the low fuel is out of question, what could it be? I am thinking the carb needs a good cleaning but would like to hear y'all opinion about this issue. Any suggestions would be greatly appreciated.

Its a stock 307 with three on the tree with 4 bar carb.