Chuck,

If the Auxillary Air Valve is Faulty, then the car would run poorly hot or could it run poorly cold as well.

The reason I ask is because my 1982 280E runs terrible cold. It starts up fine but has a lot of hesitation and stumbles and will barely idle when the motor is cold (can be 100*F outside). I replaced Cold Start and Thermo Time but that didn't help. Once the motor is above 80* C on the coolant temp gauge it runs perfect.

I was told by a couple of Mercedes Mechanics to replace the Warm UP Regulator. But on all the troubleshooting guides I've seen for K-jet point to the Aux Air Valve.