Troubleshooting Oven BBQ Cooking Times I'm having a hard time letting go of using cooking time &amp; internal temperature as metrics when it comes to cooking BBQ, especially when using the oven.

For example, I'm currently baking baby-back ribs wrapped in foil.  This recipe calls 3 1/2-4 hours at 275 degrees.  However, the ribs reached an internal temperature of 200+ degrees after only 2 hours.  

I took the ribs out and tested for done-ness, but found the meat cooked well done but chewy.  After letting them sit (wrapped) on the counter for about 15 minutes, the ribs went back in the oven at 225 for the remaining time.  

If the issue was simply that I need to cook them lower and longer, I'd be fine with that- but it's not.  People achieve great results using various times, temperatures, and recipes.  This is definitely a problem with technique. 

My question is this- is an internal temperature of 200+, after only 2 hours, not excessive?
The temperature you are reading is heavily flawed. There is no way your probe's reading will not be heavily biased by proximity to bone, and the relative thinness of the meat. 

Regardless of all that, barbecue is done when it is done. When cooking meats whose connective tissue needs to be broken down, the final temperature will be well beyond food safety levels. You need to examine other metrics to assess whether or not your ribs are ready for consumption. Is the meat pulled back from the ends of the bones? Usually a quarter to half-inch is a good sign. Does the rack bend easily when picking it up from the middle (with a pair of tongs)? Does a probe slide in and out of the meat with ease? If you tug on one of the bones, does it loosen from the meat ever so slightly? This is what you should be looking for.

TLDR: taking the temperature of ribs is wildly inaccurate, and you should not be doing it anyway. Use tactile and visual cues to determine if you are done cooking.