Rich problem

[HiTech6]

Hey guys how about some thoughts on this. Just replaced DS headgasket and had to replace a valve. Number 1 melted a plug (Fuel line had trash) and caused a lean condition. Now I have problem running rich in #5 and #6 only. I changed plugs and wires on #5 and #6 and changed coil pack and mod. Drove a hundred miles and plugs #5 and #6 black again. Car runs good until plugs foul and then starts to run bad. I have FAST XFI but am kind of lost as what to check now. Thanks for any ideas.

 

[Just a Six??]

Do you have an RJC Plate on it? That will help even out the flow.