Acquisitions are driving stronger-than-expected growth this year. Energy Transfer (ET -0.12%) has a long history as a consolidator in the midstream sector. That strategy is paying big dividends this year. The pipeline company recently reported strong first-quarter results, fueled mainly by recent acquisitions. Another acquisition, this time by affiliate Sunoco (SUN -2.09%), will help power stronger-than-expected earnings growth for the master limited partnership (MLP) this year. The company's rising cash fl ...