Four of my team, myself included, own VFC PDW's. Out of the four guns I seem to be the only one with the purple VFC motor, however the ROF between all of our guns is similar depending of the batteries we use, so I can only think you have a bad motor Beserk.
Having had my PDW since they were first released and having used it as my goto primary since then, I have only had one failure that wasn't self inflicted. My bushings wore out, which I then replaced with bearings and since then it's been an absolute naildriver.
The PDW is the best gun I've ever owned, I think I'd rather die than sel