Used to have a E190 2.6 a while back with same overheating problem. Got the fan clutch replaced and the problem went away.

Note: I did it myself and it was a pain in the b@tt. Had to entirely remove the front bumper, the radiator, all the belts in order to remove the fan and then fan clutch. Best time to replace the waterpump too.

Good luck...

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Tigger - 2001 E320