My 2013 5.7 keeps randomly turning off. Usually when I'm at a light or going around a turn. I've also noticed that occasionally the truck feels hesitant and sluggish. If I get on the gas it will downshift and race the engine but doesn't seem to pull as hard as it should. Other days it feels great. Sometimes if I'm at a light I'll step on the gas and nothing will happen for a second, then it will chirp the tires and take off like I floored it. Dealer told me they thought they fixed it with a flash but wouldn't know for sure unless it happens again because it isn't throwing any codes. After 3 weeks it just turned off again. I've also noticed it's been warmer out (50's-60's) when it doesn't feel that great. Only has 36,000 miles. Any ideas?