Pulled out of the carport this morning and the truck shuddered hard and did the same in the driveway. Got out on the road and the transmission shifted hard 1st and 2nd. Low power and the typical noise from the rear. The truck seemed sluggish on the highway and hard the hard downshift coming to a stop. Got to my destination and started to pull into a parking slot while steering left and the truck would hardly move. I straightened the wheel and backed out, no problem. Turned the wheels right, pulled forward and had the same problem. 5 hours later, backing out of the slot, wheels cut right, low power. Pulled forward, wheels cut left, low power. It was as if the truck was being held back. Once on the road, hard downshift at stops. Seemed to be sluggish. I slowed down for some railroad tracks and again, sluggish acceleration. I looked down at the cluster and the 4 wheel hi icon was on. I haven't used 4WD in at least two years. I pulled over, put the truck in park and the parking brake light came on. Mind you, I hadn't noticed the 4WD HI icon earlier. I never use the parking brake either. I hit the switch to turn of the parking brake off and set the transmission to 2WD. The only problem for the rest of the 6 mile drive home still seemed to be sluggish acceleration. Turned into my driveway and hard as I tried, no problems with steering. I put the truck in park, set the parking brake, put the truck in drive and the parking brake went off as it's supposed to do. I've about had it. I only have 26,000 miles on the truck. 2019 Sierra SLT bought new in 2020. I still owe on the loan. Anyone else have similar problems?