I pulled all the plugs, and they're perfect. Perfect meaning all identical... ~0.037". I couldn't find a direct reference to the '90 4.0L gap anywhere, and my underhood decal is covered up with my compressor.

The new wires worked wonders. My 16yo daughter even called me from school to tell me how much better it ran. Woot!

Thanks for the help! <img src="/forums/images/graemlins/kewl.gif" alt="" />