My engine is a 305 TBI, I'm getting a stumble when I warm up when driving, and it seems to happen when it is raining, or has been raining. I've replaced every sensor under the sun over the last couple of years. No check engine light either. I suspect the coil, but I'm stumped. Any input would be appreciated.

 

When was the last time you gave it a tune up? You're describing a possible issue with the spark plug wire(s), where moisture in the air can make a bad wire jump spark to ground, causing a misfire. Plugs, wires, distributor cap and rotor would be a nice treat if the engine hasn't gotten it in a number of years or miles. Also look at how the wires are run/supported to make sure none of them are resting on anything metal.

 

Hey, long time no see! I really don't remember when I changed the wires, but I checked the cap and the connections look pristine. I think I'll just purchase a new set of wires, and see what happens. I'll also check everything you mentioned.