Dogdays : Thanks for the input. Heat should not be issue as it has only happened on highway and not after stopped or slow driving.
And the heat does not change after the 2000 miles. Had even higher temp outside and GV still worked. It's deffinitly a distance/time related issue.

Triggerfish : Have called tech GV and they said it's power issue .
Something like battery to low or too high. Have changed 1 wire alternator for other type last winter and issue did not change.
Perhaps some issue like leaking pressure and this causes slippage like bands in 727 but then in GV and this makes oil dirty.

Tech GV have given me some tests to do and need to get back to them after this BS weather is gone in The Netherlands and I can give the Hemi a nice beating.