problems with 460

i have a 1997 ford f250 with a 460 in it. I'm having problems on rainy days that it wont start. if u crank it long enough it will fire up but usually u have to charge up the battery before then. it doesn't sound like its even trying to start or fire. I've herd that there's something that when it gets wet it wont allow the motor to have spark. if you know what it is it would shurly be grateful. i also have a problem with the check engine light. if you run the truck at about fifty1five or higher for more then 20 min the check engine light comes on. i haven't had a chance to plug it in yet but if you push the clutch in, turn the engine of, and turn the key on it goes away. no idea what that problem is but its been going on for a couple weeks now.

check your dizzy cap and wires I have had them to not want to crank with a cracked dizzy cap wires can also cause it the coil wire might be grounding out when wet or damp.bad plug wires or cap could make the light come hy miss firing.