Car Throttle Stuck problems of the 2017 GMC Sierra 2500

My 2017 GMC 2500 sierra denali duramax has had this throttle issue, it seems to only do it when the exhaust stinks, and at speeds between 5 - 55 mph. If I take my foot off the accelerator the truck maintains rpm (1200 - 1400) or even has increased some and has lasted 2 - 5 seconds (estimated and greatly reduces the effectiveness of the braking capacity and responsiveness/stopping distance). Worst was with a huge trailer behind and I got up to speed 55 on county hwy 8, and I let off the accelerator and it kept going hard and I got on the brakes and I couldn't slow it down until the truck decided to release off the throttle. (two witnesses in the vehicle, one a gm tech, stating your vehicle is not safe and needs to be looked at) it's happened about 25 times in 5700 miles in various settings & speeds and has occurred frequently in town at speeds of 25 - 35 mph. There maybe several hundred miles in between episodes if you will, as they occur in clusters when exhaust stinks and gone when exhaust does not stink. Truck also had torque converter not unlock and damn near choked the engine off at stop sign right after a throttle stuck condition. Got home the other night and fuel gauge stopped working! back up camera is daylight bright at night, low coolant issues, map sensor issue, engine surged the other day, what next? it's constantly been at dealerships with no answers. My wife won't drive it anymore and wishes I wouldn't either fearing it will cause an accident and she's probably right. Gm has stated they are aware of the problem but will not provide any trade in assistance dollars to get it off the road and there is no fix. $70,000+ truck, lives at risk and no serious response from gm?.