Warm-up circuit

[tonilfhs98@xxxx]

To all,
When my D is warming up from a cold start. The engine idles up and down 
like someone is playing with the gas paddle. I was told that is normal and 
Ds are designed to do that. My question is why? I do not know of any other 
car that behave that way. There must be a reason as to why it was designed 
like that. Anyone? Thanks
Bill Kwan
#2157