Ok I’m new to this forum but I have a 07 Chevy duramax lbz classic body style. I can be just driving it and it’s random sometimes it does it the day after I add coolant or week later. I can be driving it and stop somewhere and leave the truck running when I left the truck temp was 210, I get back in and it’s sitting on 160. And later it’ll puke coolant. I’ve replaced the thermostats already. I’ve read it could be head-gaskets but I find it hard to believe it could be head gaskets. Could it but something else?