So I have a 87 s4 turbo 2 with stock clutch fan and a air to water intercooler setup, it’s always been running fine and my coolant temps were always at 1/3, recently I saw my coolant temp climb to the halfway mark while I was on the highway but as soon as I get into town it goes back down, I’m running a dual alternator pulley, and I have an aluminum under tray, is it possible that my thermostat or water pump are going out ?