When starting my 90 420 on moderate to cold morning I feel a vibration throughout the car when I first reach 45-50mph. When the car warms up or about 4-5 miles the vibration is gone. The wheels are not wet, i.e. frozen water throwing off balance, etc...No vibration for the remainder of the day, car sitting or not. Does not appear to need shocks, but does have new tires, however, if balance was the culprit, why would I notice only when first driven cold...Thanks for the replies.

It sounds like flat spotted tires from parking for several hours. This is normal. This problem is worse when you park your car with hot tires over cool night. Some tires are worse than other in this regard. You can reduce this problem by putting more air in the tires.

Thanks for the response, it seems to be the most logical at this point... I'll try the fix tomorrow.