I think the new signal generator may have done the trick! I put a new cap and rotor on too, so maybe that was it. It started right up, ran fine all (dry) weekend, and ran fine on rainy monday. I need a real humid day to make sure, but I'm hopeful. The bad news... I stripped the distributor threads -- taking the cap on and off many many times, I must have over-done it. Thanks for your advice all.