If the coil is visibly arcing, I'd guess there may be a crack in the coil case. Try spritzing some water on the coil while it's running. You can try replacing the coil wire to see if it helps, but it sounds more coil related to me. Someone else may have a better suggestion.

Frank


'89 [color:"white"]G-Raider[color:"white"] [color:"black"]Supercharged 3.0L, MegaSquirt 2, lockup A/T, 2.5" exhaust, 172k, Cibie H4s/Oscar SCs, Hella Micro DE fogs, Cobra CB, Superwinch hubs, LSD rear/Aussie Locker front, Bilsteins, Lifeline AGM, Rust-Oleum