P0307 could result from a bad camshaft but could just as likely be a clogged injector (this is the end of the fuel rail) bad plug, coil, wire are any of several other things that are all more common. I would want to know HOW they determined the cam was bad? Just saying it is misfiring, and the cam is bad seems out of order.
A transient ground from poor wiring can very easily take out a transmission and often does. Make sure the wiring problems are resolved to prevent a recurrence.
Here's and article on the topic that may help you.