Diffusion-based molecular communication (DMC) is a promising technique for nanonetworks. The main objective of this paper is to evaluate the error performance of DMC employing pulse-based modulation scheme. We derive closed-form expressions for error probability using energy detection and amplitude detection techniques. The error performance model accounts for diffusion noise and intersymbol interference (ISI) effects. We compare the performance of both detection techniques along with investigating the effect of different parameters on error performance. We also evaluate the channel capacity of pulse modulated DMC.