Kelle

Hi. I recently purchased a 2008 silverado 1500 5.3l and I'm trying to solve a very bizarre issue. So when I dont plug the truck in, it starts great no matter what the temperature is. Even down to -35 it still starts fine. The issue is when I plug in the block heater. If I plug it in overnight and try to start it, it chugs and misfires like a diesel on a cold start. It'll even sputter and die sometimes. Doesnt throw any error codes. I've never seen any vehicle have issues starting by plugging in the block heater. I had a 2009 4.8 that would think the engine was overheating if you plugged it in. It would turn the ac off and turn the electric fans on. I feel like it has something to do with a wacky temp sensor or something. Anyone experience something like this before?