It's time for some real electrical help and no harassment...
The multifunction switch is the home of a lot of the electrical problems simply because it works so many things. The fog lights make problems because they route electrical power though the multifunction switch along with the headlight dimmer. The wiring will often overheat and start to melt the plastic connector shells. This causes intermittent connections that make things flicker and flash.
A trip to the junkyard will get a multifunction switch for less than $25. Be prepared to get the plastic connector shell for it when the switch is removed from the junk car.
A word of caution about multifunction switches is in order here. The multifunction switch (high/low beam, wiper, turn signals) are different for different years. 87-98 will work in any 87-89 car. The 90-93 switches only work in 90-93 cars. You can't put an early model switch in a late model car, nor can you put a late model switch in an early car.
Supposedly you can move the pins around to make the switches work in model years that are different from the car the switch came out of. I cannot verify that and haven’t tried it .
There are 3 Phillips head screws on the bottom of the plastic cover that cover the steering column. Remove them and the cover will come off. The multifunction switch is mounted with 2 Phillips head screws. The plastic connector shell will come of with some pulling and gentle prying. Examine the wiring closely and you may find several loose wires or cracks in the plastic connector shell. That means the shell needs to be replaced.
While you have the cover off, plan on replacing the ignition switch –($12-$15 at the auto parts store) . This is another known electrical problem.
There is a FREE recall on Ford ignition switches. They overheat and sometimes catch fire.
Copy down you VIN number and call the Ford dealer nearest you. Tell them you want to see if the ignition switch recall for Fords & Mustangs was done on your car. They will ask for the VIN number & check it against the master database. If it isn't in the database, then you can schedule an appointment to have the switch replaced for free. The TSB is #95S28, and don't let them tell you that they don't do that anymore...
While the ignition switch is up for replacement, look closely at the wiring and plastic connector shells for it too. They tend to overheat and crack just like the other plastic shells do. There are several instances of wires pulling loose and causing strange problems.