Won't crank without ether. Runs slow n ruff til temp comes up then runs n starts fine unless given time to cool . Then process must be repeated.

Diesel? ETHER? Coolant temp sensor--- NOT the sending unit for the gauge(unless they are the same on that engine).Scan data when sat overnight , see what the temp sensor says Or even after it has been run , either way if that is the cause , it should be way out of range. JUST an opinion , but I would avoid ether at all costs!! Try BERKIBILE 'gum-cutter' , a little safer.