This isn't related to your question, but I hope you read all the tips on plug changing. ie 13 ft lbs EXACTLY and stone cold motor. You don't wanna blow a plug. I have read too many threads aboug plugs being changed and a week to a month later they blow a plug out of the head.
If the out side of the plug is getting oil soaked it can come only from 1 place. The valve cover gasket must be leaking and the oil getting inside of the spark plug hole.
Did you clean the plug boots and hole prior to installing the new plugs? The second set of plugs could have been contaminated with residual oil.
The 98 is not a PI head and does not have the problem of blowing the plugs out as far as I know.
Clean everything with wd40 and rags to make sure it is clean.
Reinspect after driving to locate the leak.