Recently, while driving my truck, I noticed that my trans doesn't want to stay in gear. It feels like it wants to downshift, making it kind of "lunge". The RPMs fluctuate while cruising but are nothing too extreme unless I'm hitting a hill, and then the downshift is pretty hard and my RPMs skyrocket. I'm unsure what it could be, and I'm not getting any codes. Any thoughts are always helpful.

-Chevrolet
-2017 Silverado 1500 Custom
-2WD
-5.3L Gas V8
-Double Cab
-6L80E Transmission. Bully Dog Tuner with Electronic DOD delete