We study the outage performance of an amplify-and-forward (AF) cooperation with full duplex relaying (FDR). When there exists a non-negligible direct link or residual self interference (RSI), full duplex relaying turns the effective channel into a frequency selective channel. Assuming minimum mean squared error decision feedback equalization (MMSE-DFE) at the destination, we derive tight closed-form bounds on the outage probability expression for AF-FDR, and study the effect of the direct link and the RSI in the optimal duplex mode selection. It is shown that under a strong direct link, FDR becomes less beneficial due to the persistent noise amplification. Furthermore, equalizing the RSI at the destination is shown to provide more graceful performance degradation compared to a simple receiver considered in previous works, which treats the RSI as noise.