For about a couple weeks now, my toilet bowl will bubble when the sink is running. And sometime when I flush the bowl doesn't fill back up and sometimes it doesn't flush at all and will fill up and then slowly (like over night slowly) will drain down. We checked the vent on the roof and it is clear and we don't know where to go next... Please help!! Thanks

You are describing a few symptoms of separate and probably unrelated problems. The bubbling toilet caused by sink usuage is a drain trying to vent back up the toilet. You may have checked your roof stack and it appears to be clear but there is blockage down by the toilet, rod from the roof all the way to the basement fllor and then 10-15 more feet. The flushing problems needs more info before we solve that. When the toilet does not refill properly, how well does the tank refill? There is a small tube from the ball cock to the overflow tube, this tube must be inside the overflow tube at all times, is it?