oh, dude... those plugs look nasty.. It looks like a possible valve cover gasket leak plus heavy corrosion on the plug's electrode.. Definitely looks ready to replace. I don't know what it is supposed to be for the 8 cyl motors, but I could've sworn it was .040" gap? One of you 5.2l owners will have to chime in.. As far as brand, the plain copper cheapos from any auto parts place usually works pretty good from what I've heard. I believe I went with the mid-level Champions plugs(~$3.50 each from walmart) and they work like a charm for me, never had a problem. They were supposed to be pre-gapped but I had to redo it anyways, half of them were wayy too high or too low a gap.
Edit, if what you had before was working fine until recently, you might as well stick with it. It looks like champions? That name gets thrown around a lot here from what I've seen. Cheap, works just fine, copper core, good enough for a Jeep. One thing to note, don't bother spending for the premium $15 per plugs, and stick with copper plugs, not the platinum or anything
1995 ZJ ltd, 4.0 i6, *cough stock cough* 253,xxx and still pumping strong
1998 Chevy Cheyenne K1500, 5.7L Vortec, mostly stock
*In peace, sons bury their fathers. In war, fathers bury their sons. - Herodotus
Originally Posted by JasonStebbins
We can call it the Whoosh King Catalog System. :D