The issue isn't your phone, once you've unlocked it such that you don't get a PIN entry prompt when popping in the new card.
This is specific to MetroPCS, that I've never run into before. They pair bond SIM-IMEI. If you want to put your metropcs SIM in another device, you need to call them or drop by a center. The instant that he made the change in his system, this phone that I'd been laboring over suddenly worked. Cost me $10 to do this. One way that a low cost service nickle and dimes you.