Misfire after overheating
 

I'm working on my friends 2008 Ranger. It has the 3.0 v6. The radiator busted while she was driving it so we poured water in it to get it home. The next day it was misfiring on 2 cylinders. I put in a new radiator but can't seem to locate the source of the misfire.

What steps have you taken to attempt to determine which cyl are misfiring?

cylinders 1 and 4 are misfiring. Plugs wires and injectors are good. Coil does seem weak so that's what I hope it is but I did the paper test on the exhaust and it does suck air a little so is it more likely the coil of a burnt exhaust valve?

It is a little odd to have two cyls on opposite sides of the engine with a valve problem from that episode. I would get a hold of a compression tester and confirm your suspicions, if that is so. If cold water hit the hot coil, I suppose the coils might have cracked. You might be able to see a crack, but they are not always easy to see and yet spark will find them. The electronics are so designed to save the converters if there is a misfiring plug or two and the system will shut down the misfiring cyl injectors to prevent converter destruction. Make sure there is spark getting to those two cyls before diving into a job that may not be necessary.