I had asked that question earlier and didnt get the answer I was looking for.
But I found it today at a Auto Body Shop supply store.
Its called REMOV ALL Stripper, it comes in a spray can and it states that it works on all of the normal metal surfaces and also works on TPO Bumpers, Rubber Seals. I have not used it yet but I thought I would find my old Thread and add this info to it. In looking for my thread I found yours.