Pork Butt Question

untateve

This past weekend, I did my 2nd butt (the first one awhile back came out wonderful but took longer than I expected as my fire died sometime in the night).

I cleaned my Egg and loaded big lump charcoal pieces at the bottom, and medium in the middle and so on. I put a mustard slather on my 6.5 pound butt, a dry rub and got it on my Egg around 10pm Saturday. The dome temp was at 220 at 5am but by 8:00am it had dropped to 185--not a biggy--opened a the vent and the wheel and got it back the dome back to 220 no problem. Internal meat temp was around 135 at this point. Well, it stayed at 135 for about 4 hours. I increased dome temp to 250 and temp meat temp creeped to 145 but then dropped to to 143 and stayed for hours. I only opened the Egg once to check internal meat temp with a 2nd thermometer to make sure the 1st wasn't broken and once every couple of hours on sunday to spray it with apple juice.

Finally, at 1:30am, my internal temp reached 198 degrees. Thats 27 1/2 hours to cook a 6 1/2 pound butt--what did I do wrong or should I just plan on it taking this long (there was no other food in the Egg, only the butt).

All help would be appreciated.