Blinking check engine light

Does any one have a recommendation for a COP tester that can be used without disconnecting the coil? In other words does a tester that you just hold near the coil and lights or not, available since this misfire situation due to bad COP is somewhat common.

There may be an inexpensive one out there. Most garages have a scope system that is used. They are big money.
Your truck has this built in. If a COP is failing or has failed, the engine computer will set code for the individual cylinder. It might not be the COP, though, since the code is for cylinder misfire. There can be other causes for that. In most Ford trucks, the reliability of the plug and wire is good enough so that an individual cylinder misfire would assumed to be the COP.