I'm not really a 'Low and Slow' guy, I like to smoke butts a little hotter...
I like to put them on between 275° and 300°.
Verify the temperature your smoking at. I like to check gauges against a know oven gauge that has been confirmed as accurate...
OR... Boil some water and check gauge at boiling temp. (212°)
Too big a fluctuation of temps makes it danged near impossible to tell what you are doing. You may have been only warming the meat.
Don't check the meat too often, you will only delay it getting done.