'90 Geo Tracker 5-speed 145K miles fuel injected

Hi, whenever I crank my Geo on a cold day it idles at 2500 RPM's until it warms up. Then, when it's almost warm it starts fluctuating rapidly between 2000 & 2500. Then it goes down to normal once it is warm. Has anyone heard of this before & is there anything I can do?

Oh yeah, it only happens at cold temperatures.

Thanks

 

Anyone have any ideas?...I hate to start playing with the idling, b/c it stops idling so fast after the engine warms up.

 

Sounds like your automatic choke is working "almost" right. It's doing what it is supposed to do but has a little problem when it should go back to resting. May just be sticking.

 

First thing to check would be your coolant level.