It could be water in the ignition easy enough. Don't overlook C500 what is constantly getting drown.
You can save a bunch on DIS by going to salvage yards. FWD cars with this engine are common. It is pretty unusual for a DIS module to croak. Coils hold up fairly well as long as they are good ones. Don't bother with "performance" coils, especially accel. You don't need anything but stock coils for this. Often when an OE coil fails, it did so because one or more plugs or plugwires are bad.
If you don't have the metal shield between the coils and module... get one. Read the DIS article in my cave. A mising shield causes multiple problems. You may have to go to yards for it. in what case just get 2-3 whole bricks.
After checking grounds and battery cables... I would start with new plug wires, cleaning all the terminals on the brick (all, not just coil posts) and cleaning C500.
When you install the plug wires. get some cotton swabs and put a little dielectric up in the top of the boots. especially coil boots. Also coat the tips of the coil towers. Be careful... too much dielectric can make tight boots push off.
You can also coat all the other module terminals with a light film of dielectric. (The crank sensor terminals should be packed with dielectric. The actual sensor part not the module. packing the module hole just wastes and makes a mess.
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