1992 continental spark plug problem

the car has a 3.8 liter i just did a head gasket on the front head #4 cylinder was leaking. had the head planed, new head bolts , gaskets and plugs. the car ran good for 2 weeks now its running rough again . i removed the #4 plug and found that the plug actually melted ( ceramic, elecdtrode,etc.).i put a new plug in and it ran for a day then the same thing happened,this plug hole was heli coiled also. does anyone have any ideas that could hepl me? thanks:screwy:

Probably not the suggestion you want to hear but I say sell it and get a pre-1980 Lincoln. Not as many gadgets to go wrong and still a sweet ride. I own 2 that are 28 years old and one has never even had so much as a valve cover gasket changed. The other had one valve cover gasket changed and tranny rebuilt. They just don't build 'em like they use to.