I just finished R&R on my 86 300sdl. It is running great, but after warming up, the temp. jumps from 75 to 110 then down to 75 - real eratic. The car has a new thermostat and radiator. I burped the radiator when refilling(if anyone has the exact steps on this, I'd appreciate it, just to make sure I did everything right) Any suggestions as to what to check first and what might be going on? Thanks! Jeff