99 Expedition No start cold weather

I have had numerous occasions where my 99 Expedition will not start when there is cold weather. When you attempt to crank it starts and shuts off immediatley and then will not turn over there after. I took it into a dealer where they told me the crank sensor had intermitents (spelling sorry) Anyhow I had it replaced and 5 months later it started again. This time I replaced the sensor myself and a couple weeks later it acted up again. Well during the problem I found that if during that split second when first attempting to start when it cranks if you slam down the gas pedal it will start up right away. WEIRD!! anyhow so far it has not acted up again but I'm sure that will not last. Does anybody have any good suggestions???

What happens if you slightly crack the throttle? I have seen lots of IAC valves get sticky and not let enough air in to start or maintain idle in cold weather.They don't throw a check engine code, but if you crack the throttle, they start and run fine until you let the throttle close completely. Good luck with it.