I had a P0304 code. After spending $230 for computerized engine diagnosis and other electronic modern technical voodoo, mechanics warning me of head gasket problems and other expensive propositions, it was a lousy spark plug fixed for $2.00.
Where it is #6, if it is like mine it is right out in the open. For a few minutes you could check the wire and plug. wet the wire and grab hold. If it bites, that is likely the issue. If not you can swap plugs with #5 very easily. #5 is the middle on the driver side. if the problem moves, it is the plug. Well, duh, I guess you knew that.
Did you find out what it was?
95 Ranger Styleside SWB 4X4, 3.0, Auto, 4.10, 145,000 Miles
Century Cap, BF Goodrich All Terrain 30x9.50's, Reese Hitch, K&N Air Filter, Taylor Wires, Splitfire Plugs (I have had good luck with them), Bed Mat, Upgraded to factory alloy rims from "argent wheels", Cat, Dynomax Cat Back, Additional Battery Charging System, Transmission Oil Cooler, Grizzly Grill/ Brush Guard, Hella 500 Amber Fogs, Chrome Diff Cover, Nerf Bars, new bumper.
Upgraded to NH registration from Mass (Best upgrade!)
OEM Tube Rear Bumper, Tow Hooks, 31x10.50's, Larger or Additional Fuel Tank, Locker