Ignition Coils Failure problems of the 2003 Ford Explorer

I purchased a 2003 Ford Explorer in April of 03. When we took receipt of the vehicle the dome light was not functioning. The vehicle was repaired and we took over the vehicle. From about 6000 miles we had a problem with the vehicle stalling or not starting in cold or humid weather. We have had the car in for service to the dealership approximately 8-10 times a year for various problems. We have had the following concerns with the vehicle; the dome lights have been out, the rear driver window has gone out, the service engine light has come on numerous times, the light for the rear differential has come on several times, the power door locks have failed or locked and unlocked when driving the car at speeds above 40 mph. We have had problems with the vehicle stalling or not starting in cold temperatures or when it is humid or damp outside. They have reprogrammed the computer twice and replaced various sensors. The dealership also put a flight recorder on the car to try and determine what the sensors were doing at the time. On one occasion, while the auto was at the dealership, the car was in park, the car rolled backwards. We are still experiencing problems with the car starting hard or stalling or not starting and are frustrated that nothing seems to be able to be done for it. I have paid to have the vehicle hooked up to the machine and it is showing a problem with the fuel sensors now. The auto repair shop stated the ignition coils are rusty and should not be this way for the car having 60,000 miles on it. After the original 3 year warranty was up on the vehicle I told the dealership I wanted an additional warranty which the dealer supplied with no questions asked. I realize with it being an "intermittent problem" it may be hard to diagnose, but Ford has received their money for the product, I don't think it's too much to expect a "reliable" car. Thank you for your help with this matter.