I have a 2015 that came in for a check engine light on with code p012f also the exhaust filter is 95% full. The pinpoint test leads to no fault found and I think they may have left the truck running with the block heater plugged in but when I road test and monitor the ect and eot I find ect is not stable. When it is hot ect gets up to around 180 ish and then when you come to a stop it drops to 160 ish with eot still at 190 ish. I don't have another truck to compare and I am wondering if this is normal, it kind of feels like I might have a restriction in the cooling system but maybe not because it still makes good heat. What do you think, is this normal?