1987 Van won't start if it's raining

1987 toyota van, 210,000 miles, 1.5 years ago wouldn't start on Hawaiian wet/rainy days. Changed plugs, wires, distributer, rotor and it worked great for about 14 months.

Now again, it won't start on a rainy day. Looked at distributor and rotor and noticed more corrosion than I expected in such a short time. Changed them. Plugs looked good and I left them in. The thing fired right up. Went out to start it up this morning, wouldn't start :-(

I'm thinking corrosion in the ignitor assembly or coil???? Looks a little pricey to be replacing them, so I'd hate to do it unnecessarily. Any thoughts on this would be greatly appreciated.

it is only acting up when raining, are you using toyota parts or aftermarket, might be corroding quickly with aftermarket, also, would probably go with coil, is it original, could be cracked and letting in moisture, trying to remember, is it external or in the distributor on the 87, anyways, try new coil and some toyota parts