2004 4.0l SOHC misfire, backfire in intake

[PapaMelch]

what did the plugs look like , was there black wet shinny stuff on any of the plugs?

Apart from the one plug missing the electrode which was sooty, they looked normal.

 

[07gtman]

wow was that the #4 the piece of that my be the culprit got stuck in the valve hard to say, get a new plug that black plug tells me it is running rich.do the other plugs look like that. there is a vacuum leak somewhere, i would replace the pvc and hoses connected mostly that rubber elbow..that elbo is hard to find in the engine bay

 

[Drewmcg]

I'm following this with interest. Any update?