to be honest(i know this sounds like a pain in the ass) I would take and start by changing the harness in your charging circuit. Or if your handy with a multimeter, take and ohm out all of your wires. If their is high resistance, which could cause current not to get to the places it should, you should see a resistance of greater than one. Seeing as how your diode was bad, i would say the others were the same, and this could be the problem with it. If it was the regulator, that would be caused by loose grounds and connections and such. Start by ohming out the cables between the alt and the battery, and then ohming out the rest. Also check to make the block is grounded correctly. This can also cause issues like this.
i know how it goes to troubleshoot a problem like this, so i feel for ya! i drove a mitsubishi all through school, and they are notorious for alternator problems. Just start with the basics and work your way up from their.