Do you have an injector kill box you can hook up, I'm leaning towards injectors myself, I've seen it multiple times, had one a while back that had this code, initial diag - tank coming apart, wiped out fuel pump, replaced pump, tank, filter, flushed lines, good for 2 days, came back with a P1211 in it again, and ended up needing 3 injectors as proved with the kill box.