(86 IROC)Tach, Oil pressure, and light works for 10 to 20 min. then stops working. After some time they start working again. They go off faster if heat is on. Stay on longer if A/C is on. Has anyone had this happen to their car. If so what did you do to fix it. one person told me they had the same problem. After changing the heater coil the problem went away. I have changed gauge cluster. It did the same thing. Can someone let me know where I can get a new cluster circuit board. Any help will be greatly appreciated. We will miss Boyd Coddington.