rich running 3.8

[hihosilver]

Hey Mustang experts,

I own a 2000 Mustang 3.8Litre convertible. At start up in cold temperatures, it stuggles, like it is getting too much/not enough fuel/air, and it also seems to be running rich; exhibiting soot out the tailpipe, even after long highway drives. Can someone tell me, if this is a common trait/problem with a 3.8 motor. My dealership has tested the vehicle and say's everything reads to spec...Obviously they have not duplicated the problem. Please notify me a.s.a.p. It would be greatly appreciated. Keep those tires squeeling!