Does the engine now miss at idle? or only while driving?
Was it he map or mass air flow sensor you replaced?
You probably will not see arcing the coils usually go bad internally and misfire as a result. The other thing is to remove and inspect them. However with what you describe the car needs to be graphed while driving to detect the cylinder that is causing the miss. The ford scan tool the IDS will allow us to read misfire graphics on the engine sort of like an old engine scope would. I see a lot of fords that will not set codes but I can find the cylinder that is causing the problem by using the graph. It may be a good idea to have it graphed to detect the cylinder. We do this a lot for the shops around us and generally charge 70.00 to do so.