Originally Posted by
bsell
Sounds heat related...did you check all of the other connections/wires back to the battery to include cleaning all of the grounding points?
I wonder if you have a rotten cable running along the floorboard from the engine to the battery that gets hot and resistive over time. I swear I've seen this kind of mess before and finally found it by flexing a positive cable and hearing the crunching noise from the corrosion under the insulation. To look at the wire, you wouldn't have suspected it was garbage but once I cut the insulation off of it, what a mess!
You can find the culprit, you just have to hang in there and be thorough in your search.