My 99 taurus will not start while it is very cold but will when it warms up. it just started doing this last week. i tried changing the coil pack but still does it.

Change your coil packs

CHECK TRANSMISSION FLUID LEVEL COULD BE LOW.IF ALL IS GOOD DO A FILTER + FLUID CHANGE.BEFORE GETTING READY FOR TRANSMISSION OVER HAUL.

Replace the coil for number 3 cylinder.

check your vacuum line and the electrical systems

Your car's computer has sensed a problem with your coil pack. the thing is, it could be your coil pack but it could be that something else is effecting the performance of the coil. Example; Plugs, wires, wiring to the coil pack. Look at the cars maintenance history, it might help in leading you to an answer.

check out the injectors and the coil pack to make sure you are getting spark

The concern is likely caused by the coil which sits on top of the spark plug. Your P0301 indicated misfire on cylinder 1. Your P0316 indicated it occurs on the first 1000 revolutions. Your P0171 indicated lean on bank one. Bank one includes cylinders 1,2,3 and 4. Your lean code is strange but could be related to misfire. I would recommend swap the coil on number one with number two. Clear the code and drive it. I would expect to see a P0302 which indicates the misfire traveled with bad coil. good luck.

i had the same problem on my 99 metro and it ended up being a bad ignition coil pack.goto ebay and buy the general motors tech manual. i highly recomend it.

The reason the check engine light is flashing instead of on steady is because it is missing bad and the car companies did this to tell you to stop the car as soon as possible to prevent damage. That is the only time the light will flash off and on instead of being on steady.
The cause is a little harder to diagnose. It could be a fouled spark plug, a bad plug wire, an injector, stopped up fuel filter. I can't remember if that car has the distributer or the coil packs but you could have a problem there. If you have never changed the spark plugs or fuel filter, it is well over a hundred thousand miles to do so now. They say to change them at one hundred thousand but 50 to 75 thousand is better and you will get better mileage. The fuel filter needs to be changed every 20 thousand miles now days because of all the cheap gas we have to put in the cars.
This is for mechanics or technicians. If no one out there believes me about the mileage on the fuel filter, then take the filter off and see what comes out the back. Looks like black water to me.

Check all of your connections at the coil pack. Ensure that the coil packs do not have any corrosion under them were they connect into the base module or any of the connections, even plug wires. I had this same problem with my 2.2 in a 99' s-10. Pulled the coil apart, cleaned it up and and put di-electric grease on it, all better.