02 yukon denali has trouble starting in cold weather.

how cold is it outside when you try to start your yukon, what weight oil do you have in your engine, how many miles are on it and does it run better after it warms up?

140000 miles oil is synthetic and whatever the manufacturer recommends and once it starts it runs good but when idling at a stop light it seems a lil weak. Temp is 20- 35 degrees. Thanks

Have you tried a fuel stabilizer? And did you look up the specs for oil when the weather is below freezing? Sometimes the manufacturer will suggest a lower weight oil when the vehicle is in areas below freezing.