Had a similar issue; replaced a brand new Wahler thermostat with a Behr, no difference.
Replaced the heater valve, as well. Also no change.

Issue turned out to be a broken transmission thermostat; the one near the bottom of the expansion tank. I replaced that, along with the expansion tank and the temps came back to "normal".

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12 E70 3.5i xDrive
03 E46 330i ZHP
01 E53 3.0i
98 E36 323is
12 Audi A4 Quattro
79 Triumph Spitfire
73 MGB