P0304 MIL on/off often... Looking for advice... 2011 T&C
 

Bought the 2011 T&C used in November 2016 with ~75k miles. Van currently has ~85k miles. Covered under Mopar certified vehicle warranty 100k and we bought an extended warranty as well just cause it was used and it didnt cost much.

MIL has come on and off here and there for a while now, wife drives it but doesn't drive it every day. She stays home with the kids during the day.

Decided it was time to look into it. I replaced the all 6 spark plugs and the ignition coil on Cylinder 4 this past weekend. MIL went off, van drove great for about 30 miles. This morning she is headed out and it is back on. I have her go get it scanned at Autozone and its the same P0304 code.

I know the TSB 09-002-14 REV. B is out for this but I'm trying to avoid a costly bill by having the dealer diagnosis as something else and not replace the head under the TSB. I guess the only way for me to be sure is to do a leak down test on the motor before going to the dealer?

I read that it happens on the even side head, but more often on Cylinder 2, has anyone had their head replaced for issues other than Cylinder 2??

How did the old sparkplugs look like ?, it can tell much more about the your engine status.

Can not recall exactly from memory but I have them at home still laid out on the work bench as I took them out. I believe it was a whiter color than the rest. Also appears that electrode was smaller than others and the gap appeared a little off.

What would that diagnosis generally mean?

I was able to clear the MIL last night did some driving around and it turned right back on for the same cylinder #4 code...

re. sparkplug color and condition

I would guess lean fuel mix cause high combustion temp . reason could be a bad fuel injector.