Proper characterization of the millimeter-wave (mmWave) propagation channel requires measuring the power angular-delay profile of the channel which includes angle-of-departure and angle-of-arrival of the multipath components (MPCs). In this paper, we first describe in detail our rotating directional antennas-based 28 GHz channel sounder. Then, for this specific sounder class, we describe and address the following two problems in extracting the MPCs from the measurements: 1) For long-distance channel measurements, triggering signal cannot be generated for the TX and the RX using a single clock (SICL). This necessitates the use of separate clocks (SECLs) which introduces a random timing drift between the clocks. 2) As positions of the antennas change during scanning, total distance traveled by the same MPC differs at each measurement. These problems together cause missing some of the MPCs and detecting MPCs that do not exist in reality. We propose an algorithm to correct the clock drift and MPC delay errors due to the rotation of the antennas. We compare the MPCs from the SICL measurement and the corrected SECL measurements using a Hungarian algorithm based MPC matching method. We show that the percentage of the matched MPCs increases from 28.36% to 74.13% after the correction process.