Starts but wont run..i usually buy a valet key from the dealership..this time

What is your question?

Since all the keys have been bought for the car wil getting the new ignition disable the theft deturant system so the car can start and run? if the car wont recognize the current key how is it going to recognize a NEW KEY Starts but wont run..i usually buy a valet key from the dealership..this time they said all the keys allowed for the vehicle have been bought, so they said i need to buy a new ignition cylinder and key set, if the car wont recognize the current key will it recognize the new key? will the theft deturant system allow the car to start and run?

What makes this problem better or worse?

nothing either way

How long has your 1998 Mercedes-Benz ML320 had this problem?

a couple times..this time a couple weeks