I have two issues with my 06 auto 4.0 Ranger.

1) 2-3 shift flare - noticed this not long ago but it looks like there's a lot of documentation around it, notably a new valve body and replaced EPC solenoid seems to address it.

2) Main Issue - If I am cruising along in 2nd. I've noticed that if I let off the gas the truck will buck forward a bit on the gas release to cruise. In 3-4K, it's more noticeable. I know it's a 2nd gear issue because if I drop the transmission into 2 and drive around holding gear, the buck is most certainly there.

I'm wondering if both issues are connected? if not, what could be the cause for the 2nd problem?

 

It's possible they are connected

You have the 5R55E trans, in an '06 which is a 4-speed like the 4R or A4LD, it predecessors

Ford added software to the Computers that will engage OverDrive while still in 1st, this added a Faux 2nd gear, that made for a smoother transition, from the wide spaced 1st and 2nd gears on the 4-speeds
4R was 2.47 / 1.47 / 1.00 / 0.75
5R was 2.47 / 1.87 / 1.47 / 1.00 / 0.75

The 1.0 difference 2.47 to 1.47 require high reving in 1st and then a lugging in 2nd
Adding the 1.87 made it smoother, and just turning on OD did it, very clever.

5R55E is now a 5-speed, cool, but a 4-speed in sheeps clothing, lol.

All automatics run on pressure, always have, thats what the solenoids control, they route the pressure to shift gears
Valve body has the passages for that pressure, solenoids are the "gates", so valve body problem can mean pressure is not staying stable in a specific passage.

Always just guessing where automatics are concerned, they are not that complicated, the problem is that the systems are interdependent, pretty much all overlap so a specific "here it is" answer not always available.