The blower should not be stopping for any reason, so you have a bad board or motor. I assume here the capacitor is good as the motor would not start smoothly if it were bad. The motor would run constantly on an open limit for obvious safety reasons. Get a voltmeter and see if you get power to the motor when it stops. If there is power then the motor is bad and if you have no power then the board is bad. Measure between the neutral and low speed wire that go to the motor with your meter to see what is what. Sometimes a bad solder joint on the board causes these issues, so you may want to look at that to save a few bucks in case the issue points to it.