Did you clear the codes after?
If you are not getting physical signs of missing/stumble then just clear the codes.
My first thought was everything that you have done except I'd also check the coil pack.
A link that may help; http://www.obd-codes.com/p0305
yea i did coil pack also ive replaced alot of stuff... you guys here have been a great help!!!!!!!!
only other thing i can think of is head gasket got messed up but never know with spark plug
truck runs great when driving just at idle little rough
the engine may be harder to start
the engine may stumble / stumble, and/or hesitate
other symptoms may also be present
A code P0305 may mean that one or more of the following has happened:
Faulty spark plug or wire
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector
Burned exhaust valve
Faulty catalytic converter(s)
Running out of fuel
If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.
If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors."
I really don't think it would be the head gasket but a compression and leak-down test would tell.
i have only seen plugs that bad a few times one time i used too much octane boost and well my plugs melted like that one in the pic. i recommend you pull the valve cover to see if you bent a valve turn the motor over until the 5 valve is free and tap it soft with a hammer or just see if it sits lower than other valves