Man sorry to hear that you are still having problems. Like you said back to basics I would double check the part number for the pads to make sure they are the rite ones. Also they are made by humans so they could be defective. Maybe return them for replacements. Say they don't fit right?
I ordered them online. I had them on car for couple weeks before prob started happening. I called Ford garage and mechanic said he's never heard of my problem before, in other words it be expensive for them to look at. But his best guess would be rod in MC not letting go. MC is only 5-6 weeks old but I guess I'm going to buy a new one. I think I got that MC from rockauto or CJ pony. On eBay they have booster, proportion valve and MC for $65 so I might switch it all.