Folks I posted recently on a severe multicylinder misfire that developed suddenly (I mean in an instant going from fine to very rough running) on a long trip in the mountains on a hot day. Using your suggestions and my ideas I think I've eliminated fuel system problems, vacuum leaks, idle air control, maf sensor, stuck EGR valve - and replaced plugs, rotor, cap and wires.

I don't have a way to test ignition coil and power stage other than coil resistance (which checks correct).

The ignition coil makes an audible tick when engine is running but shows no visible arcing over at night, nor does its behaviour change when sprayed with water. I'm inclined to bite the bullet and replace it. I understand a coil can fail at high temperature or under heavy load without having a shorted turn or other problem which a resistance check would find.

Does anyone have recent experience where they verified that misfire was due to a coil failure? The 850 1995 has a single coil ignition with a distributor.