Did Sai Baba ever break his promises? I heard he told a devotee named Dev he would come to a meal but then never showed up.

This is a common misunderstanding of the event. Sai Baba never breaks his word. As recounted in Chapter 40, when Dev invited Baba for an Udyapan ceremony, Baba promised to attend. While Dev expected Baba to appear in his familiar form, Baba instead came in the guise of a Sanyasi. He first appeared alone and later returned with two companions for the meal, exactly as he had hinted he would. Dev, under a 'veil of Maya,' failed to recognize Him and later complained in a letter to Jog that he had been deceived. Baba later clarified, 'for the sake of My word, I would die; but the words from My mouth shall never be otherwise.' Thus, Baba did keep his promise, but in a way that tested his devotee's perception.