Problem appeared after a rebuild of the carb, but it only happens when driving.
When driving over 50km/h throttle seems to stucks like i would have an cruise
If i put more speed it always stays there even if drive uphill, only when i press the brake really hard the speed tsarts to drop and when the speed gets lower than 40-50km/h i can hear i big click beinde gauge cluster and the speed drops dramatically (throttle realeased).
Throttle linkage are fine and this only happens when driving.
Any ideas ?

 

Found the cause of this wierd problem. High idle solenoid is causing throttle stuck.
I still don't now why the solenoid is engaged wehn driving.
Any ideas ?

Workaround: unplugged the solenoid, but still can here the relay behind gauge cluster..

 

That high idle solenoid is the A/C kicker, i'm guessing.
It's probably mis-adjusted, and you have your A/C on.