I have a 2000 Lincoln LS v8. She was running like a dream until about a week ago. She would stumble upon accerleration at about 5,000 on the tach. Naturally, I did a tune up...changed the plugs and put Bosch +2, changed the fuel filter, changed the air filter and changed the oil. She ran well then the stumbling grew progressivly worse and the check engine light came on. I had a test on it and it shows that #4 cylinder has a mis-fire. Addtionally my cooling fans only engage when I apply throttle, causing an over-heat. I checked all the coils, plugs, and listened to the injectors on the passenger side. Everything is in check. i have no blown fuses and my relays and solenoids ok. Somebody have any clues? I am about to buy a diagnosis program to load on to my computer to check all the sensors........I don't know if my problem has to do with the "fail-safe" cooling. anything would help me...thanks

Did you replace the coil on top of #4? How did you "check" the coils?

Did you check for the famous Oil in the plug galleries problem?

When's the last time you changed the thermostat? Did you check the Water Thermistor, to make sure it's good?

Why would the car overheat WITH the fan on? That just don't make sense.

ps. You might want to use the search feature, too. I hear it works really well.

No i didn't replace #4 coil. I took out the coil and grounded it to the block while it was running to see how far the spark would jump. The spark jumped a huge gap. the coil is good.

There was not any oil in the plug housing.

have not made it to the thermostat yet....maybe tomorrow

i have an hydraulic cooling fan and it will not kick on at idle. it only engages when i hit the throttle.