Flying into GED today at 3.5K. New engine purring like a kitten everything is fine until I notice the EGT on #4 is WAY low. I'm getting a 120-160 degree differance and a warning,  Engine was still running smooth but on approach #4 cylinder indication went away completly. Now I'm sweating a bit but, thinking..."man this thing runs pretty smooth on 3 cylinders!  landed and checked all connections nothing loose or broken and on start up everthing is fine. On run-up,  the same thing happens. #4 goes away. I turn the JPI off then on again and it comes back and reads fine the rest of the flight. So where's the problem...Indicator or Probes?

Jim Bunn
N1089J
1973 112
Fort Meade, MD (FME)