Dave is pointing out a known issue. The ignition control unit is mounted in the passenger side pod and can get wet if that pod drain is plugged with crud.Check if water is sitting in the rightside area above the rear fender. I don't remember what is in that area, but the drain line can get clogged and cause problems.
The distributor cap is located a few inches to the left of the timing belt in your photo.I can't say this happens for sure - but perhaps this drain causes this - which is located right above the distributor cap.
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