My pyrometers been bouncing around the dial lately like a set off double D's on a jog. Goes up to 1000 down to -200 just wacky. I checked all grounds all wires etc everything checks AOK. Their Autometer Lunar Series guages. When it happens the needle just goes crazy, then returns to what I consider the "right" temp. It will bottom out to the lowest possible temp(the close side of 1600* or 5pm on a clock) Cant figure it out...Is it the guage or something else I can check out. If it happens at night time, the guage lights dont flicker or flutter...so I dont think its a grounding issue. Any Ideas?