The MLP's growth engine is about to rev back up again.Units of Energy Transfer (ET -0.80%) currently sit about 18% below their high from earlier this year. That decline is largely due to short-term headwinds facing the master limited partnership (MLP). However, the company's headwinds should fade over the next year as stronger long-term tailwinds take hold. That makes its dip look like a great buying opportunity for those with a long-term mindset and are comfortable with receiving the Schedule K-1 Federal T ...