Most of those 4.6 ford V8's dont use COP's. Check the plug and the wires. My guess is you have either a bad, or loose plug or a bad connection between your plug and plug wire.

My suggestion on the front end is to Inspect, Inspect, and Inspect the front end parts to include idler arm, tie rods and tie rod ends, wheels, shocks and shock brackets, and ball joints. Look for the easy stuff first before testing the ball joints. It is not uncommon to break off a shock bracket when going over a big bump. If so, you will need someone to weld on a new one.

 

He's got an 02 according to another post. Will have COP's unless its a 4.2. But your absolutely right about inspecting the suspension & steering systems. You can never be too sure.