The fat should render out during the cooking process. undercooked for sure. If you want to try a hybrid cook (2 temps), try starting at 250 for 1 hour to lay some smoke on the meat, then raise temp to 300ish, even as high as 325 to power though the rest of the cook. At 300, the meat will render beautifully, and you'll be left with succulent meat.
I don't believe for one second that changing temps mid cook affected the outcome, but I do believe the temp you thought you were cooking at was a lot higher than the actual cooking temp. Cooking too low n slow will get you jerky. I know, it's the opposite of what some experts say, but it's true, food will dry out more at too low of a temp due to the length of time it has to stay in the cooker to get done. More like dehydrating than cooking.
Get an el cheapo oven thermo and toss it on the grate next to the food. That is your cooking temp.
Rescued 22.5" OTS. SJS Mini-WSM. HEB briqs (rebranded Royal Oak). Pecan/Hickory/Cherry/Apple/Peach woods.
2016 Fuji Absolute 2.0 LE (for burning off all the great BBQ)