EMS 10 shock cooling msg on all 4 cyl in cruise

[Werner_Schneider]

I have a bit over 600 hrs on my Lyc O-320 and the EMS 10 is in place for over 450 hrs and so far did perform as expected. Today on my 3hrs flight back from Vienna Austria, just behind Munich, after around 1.5 hrs flight it started to behave erratic bringing in cruise every other minute a shock cooling message the CHT's stayed stable in between 2 deg all the time I've wiggled on the DB connectors but could not steadily reproduce this error. Any ideas or what to look for?

Thanks Werner