clean every terminal/connection from the batt positive post to the bulkhead and the same from the bulkhead to the coil. if that dont do it you might go under the dash & clean every terminal/connection in that path. before going under the dash I would clean the batt neg post/clamp & the other end of that cable to block & braided cable from block to firewall (the ground path) as it (neg return side) might be contributing some to the total problem & pushing the (positive side) voltage drop over the edge tow here it wont fire (& working under the dash is a pain)