I drive a 1988 Pontiac Le Mans with an annoying starting problem. Whenever it's damp or rainy I have to remove the distributer cap and dry out the condensation on the inside with a rag to get it started. Once I get it started, it will be ok until it sits for a long time and I have to do it all over again.
Personally, I'd leave it on the side of the road somewhere and never look back. This model Le Mans is about as low-grade as they come.
Anyway, if the spark plug wires are in good condition, and the ignition coil is supplying the proper voltage, here's my suggestion. Your car originally came out of the factory with a plastic bag covering the distributer (no, I'm not kidding), and if it's still there throw it away.
Next, replace the distributer cap with GM Part # 10457153. This cap uses Aluminum instead of Zinc terminals to aid in starting and performance in damp and cold weather.
You should also use the R45XLS A/C Delco Spark plugs gapped at .045" regardless of what the decal under the hood indicates. When all is complete and hard starting persists, move to a less humid climate, or get a new car.