Yup.... to much time and/or juice when foiled. 3-2-1 is a good place to start, then as you get to finding out what you like you can adjust those times. I found I like to have a good bark on my ribs, but not have it tough, so after much trial and error I found that I like it best when I cook them entirely without foil, then pull wrap in foil with no liquid added, wrap in a towel and rest them in a cooler for 1 hr. The cooler time softens the bark just a tad, and lets all the juice redistribute in the meat. I get a nice little tug, but still comes off of the bone cleanely.
But keep in mind that is how I like them. Ribs are very subjective so try what you like. A good rule of thumb is to start unfoiled untill you see the meat pull back from the tip of the bone approx. 1/4" (roughly 2-3 hrs.). Then if you want to foil do so with only about 3 or 4 sprits of apple juice and put back into the smoker for about 1 to 1 1/2 hrs. Then pull from foil and put back on the smoker for another hour or so.
You will find what you like best and how to achieve that with practice! So fire up the smoker, invite the friends and family over, crack a few beers, and do some "research"!