My 73 450SL with 249K miles has had a problem since I bought her 3 years ago which only occurs when it is cold outside (35 degrees F or less). When I crank it, it starts a cycle of loping. I was told it was the airslide valve and replaced that with no change. I finally backed down the idle and it lessened the problem. So, now in the winter, I lessen the idle and then put it back in the summer. I am told the decel valve is shutting down the injectors and getting into a ping pong effect. It always stops at the same exact temperature or if I put it in gear and slow down the RPMSs. Anyone else encountered this and fixed it? I almost have to think that a sensor is causing it or maybe a design problem that could be cured with adding a resistor in the temp sensor circuit but that is just a guess. Thanks.