It seems like you have a couple different issues which should be easy to resolve. I have several of these and they are great machines with a few tweaks. The issue that you're seeing with the X axis is a known issue on lots of these style printers. Although it could be the stepper driver it is much more likely to be a bad stepper motor cable (and probably the end stop cable as well). I had the same thing happen to mine after about 200 hours on it. Those cables aren't rated for the flexing they get and they will eventually fail. I found a broken lead on one of the wires. It is usually intermittent and when it opens the motor misses steps and clunks, etc. You can unplug it at the MB and use an ohm or continuity meter to check each wire for sure. When I found the bad spot I could see it open and close if I pulled on that part of the wire. The gray endstop cable (my printer included a spare) can fail where the wires internally short and cause an intermittent short from 5V to ground. From your description I would go ahead and replace them both. I've only had to replace it once but I now keep spares onhand as I look at that and a normal wear part now that will need to be replaced again.
The PowerSpec 3D Pro is basically a FlashForge Creator Pro except is has a smaller 320 Watt power supply which can cause lockup issues since it isn't large enough. I ran into two printers that did this. The recommended fix is to replace it with the same heavy duty 350 Watt power supply that the Flash Forge comes with. You can get it from Mouser for around $50 plus shipping. It is a Mean Well SE-350-24 and is a direct bolt in replacement. I've done this upgrade on all my printers. It will resolve and prevent odd issues with the printer. Just make sure that when you install the power supply you check the input voltage switch and set it correctly. They come set to 220V and I had to flip the switch to 110V. If you don't switch it for the correct voltage it will cause problems! That it why I think the PowerSpecs went with the smaller 320 Watt supply since that has a wide input voltage and doesn't need to be set.
When you have the bottom cover off also check/tighten all the screws where the wires attach to the connectors and also the screws on the power supply. I've seen several cases where those screws were loose from the factory. With all the shaking from the movement as they built things it is good to recheck every once in a while.
From what I have found it came from the factory with an early release of Sailfish 7.7 with the name changed to Version 1.2 on the display. One nice thing about these printers is that they have the 2560 processor with the extra memory onboard. I've upgraded all of mine to the latest release of Sailfish 7.7 from Thingiverse (ReplicatorG-0040r33) from: http://www.thingiverse.com/thing:32084
You need to press and release the reset button on the printer just before uploading the new Firmware. Definitely worth the upgrade and I have done it on 8 of these printers. and two MonoPrice printers (didn't need to press reset on those) The firmware is the (Creator X/ Creator Pro wth 2560 chip) You can verify the chip by looking at your board before the upgrade.
Once you're done you'll have a Flash Forge Creator Pro (for a fraction of the price) and a solid work horse of a printer!
There are also some upgrades on Thingiverse (clips, etc) that make the printer easier to use. One is also running the glass bed upgrade which makes printing with ABS a pleasure.