kizer, you've reached the established "plateau," an important part of the cooking process.
I usually plan for 2 hours per pound of (individual) butts, so for 4 pounders, it would be 8 hours, plus 1 to 2 hours of leeway cooking time, plus 2 to 4 hours of resting, wrapped, in a cooler. A total of ABOUT 12 hours to cook 4-pound butts.
Others here will advise foiling and putting them in the oven in order to shorten the total time. I'd say foil your meat and put them into a 300•F oven until they reach about 190•F internal. Let them rest for a while, then pull.
Since you haven't gotten any answers yet, I'm writing this on the fly, but I know that others will improve on this.
Rita