Hello Bobby,
I would suggest that you first install the update patch for RealBand, to eliminate a couple of possibilities.
http://www.pgmusic.com/support_windows_realband.htm#2010_5_2bNext, I would suggest that you try playing the song in Band-in-a-Box using the same synth (i.e. Forte or TTS-1) if you haven't already. This is to confirm that the problem doesn't happen in Band-in-a-Box even when you are using the same synth.
In the mean-time, you should know that RealBand does have a very flexible way to search for and delete various types of events. To delete all controller 64's with a value of 127 (sustain on), you could:
1. Select the region of interest. One way to select a whole track is to press Ctrl+A
2. Edit menu |Cut, and select the "use data filter' radio button. Press OK.
3. De-select all checkboxes except for controller, set 64 to 64 as the range, and set 127 to 127 as the value. Press OK.