Well the first problem is travis posting
The colder it is outside the more dense the air is and the more fuel its going to use. If the car is tuned in very cold weather its going to use more fuel then if its warm out. This is why i said the car is going to run very rich in the summer once its warm. This also applys to people(including myself) that have gotten their car tuned on a hot summer day, you have to watch the AFRs when beating on the car on late summer nights when the temps are in the 50’s, car could go lean