cold weather starts...engine sporadic reving
 

Anyone have any suggestions on what I need to do...

Since the weather has gotten colder..below freezing. When I start up for the first time..she turns over fine but the engine will rev up to 2000 rpm for a second or two then drop to almost stalling then the sequence starts over again for about a minute. Then she's fine. Also if I start up later in the day when the temps are above freezing...no problem. Any ideas?

Oh, it's a 03 Montero Sport.