I was struggling with this problem recently and I think it is finally fixed. For me it was a poor engine to chassis ground. The negative battery terminal to chassis ground cable and the engine to chassis ground cable are both attached to painted surfaces of the body/frame. They rely on the bolts that attach them to carry the current. The problem is that the bolts that attach them have a coating that seems to be slightly resistive and I'm betting it gets more resistive with age as it took my FX 15 years before it started having issues. There is a tech service bulletin about this, ITB11-017 which describes the fix as replacing the cables but more importantly removing/cleaning paint off under the points where they contact the body and replacing the 4 bolts that attach them with a new part number that nissan refers to as an "ECM screw" which is basically a conductive bolt for attaching grounds. They also recommend replacing the bolt at a major ground point under the passenger side of the dash where the ECM grounds. This is also important. You don't necessarily need to change the bolts to ones from nissan/infiniti, as any quality stainless bolt would also work. You don't necessarily need new ground cables but cleaning paint of under the ground straps is key to this working as well as changing the bolt under the dash. I hate to admit that I killed 4 oem coils and 4 more replacements before I discovered all of this. Its been a few months and everything is great under there. No more blistering coil packs and no more misfires. Also I have never heard the engine crank over as fast as it does now.