When checking the grounds I found the same issue- the wires from the alternator were against the left valve cover just above the exhaust manifold and the black spiral wire cover had melted. The actual wires had the insulation showing signs of melt, but not all the way through. I double checked them, pulled them away from the manifold and valve cover, and added a new spiral cover. However, that did not change the issue of the three idiot lights going on and off.

This is something everyone should look at for the Gen II 3.5 engines. The wire supports do not hold the alternator wire group sufficiently away from the manifold and valve cover.