Transmission Stuck In Gear problems of the 2013 Dodge Ram 3500

The contact owns a 2013 Dodge Ram 3500. The contact stated that the odor of diesel fuel was present inside the vehicle. The contact indicated that the odor was present when the weather temperature was below 50 degrees. The vehicle was taken to the dealer, who could not diagnose the defect. The contact also indicated that while driving and releasing the throttle, the vehicle would continue to accelerate. The vehicle was not diagnosed or repaired. Additionally, the transmission became stuck in 4th gear and the vehicle would not accelerate over 5 mph. The vehicle was taken to the dealer but he was unable to diagnose the failure. The manufacturer was made aware of all failures. The failure mileage was 6000.