In recent years, due to the low complexity nature of the turbo processing and excellent bit-error-rate (BER) performance, designing turbo-like receivers for frequency-selective MIMO channels has been of great research interest. The performance gain in turbo decoders is due to an extrinsic information transfer (EXIT) process between the detection and the decoding stages as compare to a traditional system that treats these processes in isolation. However, the challenge faced with these iterative receivers is the understanding of their performance and convergence behaviour. In this paper, we study an iterative maximum a posteriori (MAP) receiver for MIMO orthogonal frequency division multiplexing (OFDM) channels and its convergence behaviour. We analyze the performance of the proposed transceiver system with Gray and anti-Gray mapping using EXIT chart and study the effects of various settings of transmit and receive antenna on the turbo cliff in BER performance.