Questran helped with having more formed BMs, but I still suffered from frequency and urgency issues just like what you described.
I was prescribed Elavil (amitryptaline). At a very, very low dose (about 12.5 mg), it controls the urgency and frequency 90% of the time.
It's too low a dose for clinical depression, it works on the receptors in your gut quite well. You may want to discuss this with your MD or GI specialist.