Hello I have a 2018 Silverado (6l80) I’ve recently had my transmission rebuilt along with a billet converter installed about 6 months ago. Truck runs fine but I’ve noticed my temperature get up to 200-220 when at idle. Once I hit the road it drops down between 170-190, when running on the highway I’m at 150-170. I’m also running a sure cool for the thermostat. Any idea why it would get up to those temps during idle ?