Airflow per rev will peak at the moment you reach full boost. Volumetric Efficiency generally goes down as RPM increases, so it makes sense. Airflow over time will peak at 6500 rpm or so on stock manifold/normal cam cars. With SMIMs and larger cams it moves up, or at least doesnt drop off as sharply if at all to ~8k. Torque will tend to follow airflow per rev (cylinder pressure) and HP will tend to follow airflow over time (HP is work done over time).
9 samples a second with 3 items becomes 3 samples per second, or a capture every .33 seconds or so. I'm not sure that correlates with the gaps in the RPM between datapoints. But this is one of the many drawbacks of using an OBD2 based system. Oddly enough, with DSMlink the 2g ECU is twice as fast as the 1G, so for once the 2G guys get the sample rate advantage.
I get over 200 samples/sec, just for reference.