Hey guys hope you guys are doing well but I'm having some problem, it happened in the morning when I was driving my 370z and I see my coolant temp going up close to high and then drops to the middle and back to high, I later then bought a thermostat and replaced it and flushed and added new coolant, I took it for a ride and it stayed in the middle but when I press the accelerator it starts rising in temperature and its cold outside but it seems like its smoking more then it should be and I smell some sweet and nasty smell from the cabin. I haven't seen any check engine lights on or a code. Could it be a coolant temp sensor or worse?