When the ribs are about to cook look for an internal temperature of 170°F/75°C and start to prepare it for serving, crispy or tender. Smoked ribs usually have a tender surface but if you want them crispy, just remove them from the food smoker and place them in a high level of direct heat for 2 minutes.
After which, you can sauce it when it has cooled and returned it to the smoker for a bit, for the sauce to sink. You can also apply the sauce and just serve as the smoker can at times soften its crispy surface.
However, if you do not want it crisped, apply the sauce towards the end of the cooking. If you opted to wrap it, just apply the sauce immediately you remove the foil.
In relation, by saucing and continuing to smoke it, you will only get more smoke into the sauce, making the pork ribs sticky, avoid this by adding more and more sauce. For smoke flavor, add more wood.