4L60E goes in drive while shifter is in neutral

[NBS4x4]

Newbie here on the forums. I'm hoping to narrow down my issue(s) with y'alls help and would like to thank everyone in advance.

Just rebuilt a 2005 4l60e on my 2005 Sierra RCSB 4x4 and when I first put it on the ground reverse worked fine. After driving it about 30 miles, I noticed that when I put it in neutral it still tries to drive forward. It will still start in neutral but then the truck would jump forward. When I put it in reverse, acts like it's in gear but no movement. Is there something I can check before having to drop the transmission?

[CamGTP]

Make sure the shifter cable on the transmission is adjusted right.

[NBS4x4]

Well after taking the transmission back out and tearing it back down, I realized where I messed up. I had the sprag gear backwards, the sprag assembly was rotating clockwise instead of counterclockwise. Got everything put back together and back in the truck. My luck, another issue has come up. Now when it hits 4500 rpms or so, it all of a sudden jumps out of gear like I revved it up in neutral.

It does it when it's in D, but shifting manually it holds the gear like it supposed to. I wonder what would cause this, if anyone has any inputs, please say so!