I took my car out yesterday at about 6am, the air temp was in the 50's. So after the 2-3 times I had to crank it to get it to fire up it barly wanted to stay running at idle. The whole car was vibrating around me for a few minutes untill it warmed up. Now if I had tryed to start it later that day when air temp would have been around 80-90 it would have fired right up and idled smooth as silk like it does on a daily basis.Could it be running too lean when the air's so cold so maybe a choke problem?