i have a 99 escalade that will not start in cold temperature, say 40 degrees or lower, warm temps its just fine. it will usually drain the batteries and you have to jump it off then, and it will finally start. it acts just like an older vehicle that will not start if you dont set the choke. i have changed the water temperature sending unit and the ambient temperature sensor by what some local mechanics have said. this is the third winter with this one problem. theres got to be a fix.somewhere please help me fix my wifes ride.

IAC valve could be an issue. Try cleaning it.

How many miles on the spark plugs? Have you tried a shot of starting fluid, and what did that do?