Gradual Choppy Audio Failure in Mainstage

Hi, today I purchased and downloaded Mainstage 2.2.2 for my Macbook Pro (Early 2011, 8GB Ram). I also have a similar issue with Mainstage 2.0 on my 2009 iMac, I hoped the problem would've been solved with the new version, but the exact same one exists.

I use a Presonus FIrestudo Mobile for MIDI and Audio hookup in Mainstage 2 via Firewire. The MIDI works perfectly with my keyboard. When I plug in guitar orvarious keyboards for audio however, they work great for about 30 seconds, then they start introducing static noises along with distortion as if the CPU is overloading, but the CPU meter is fine.

I've tried everything so far, the buffer size, toggling I/O latency settings, updating my driver, switching the soundcard settings, firewire cables etc. The strange thing is, whenever I change a setting on my soundcard or in Mainstage, the problem goes away completely for about 30-45 seconds, and then comes back. Its very upsetting.

ANOTHER strange thing is that I use the same setup for recording in Logic, and I've had this exact same problem in the past, but then I switchedd Plug-In Latency in audio prefrences to 'Off' and the problem vanished permenantly. This leads me to believe there is a similar problem with Mainstage 2 software, but there is no Plug-In Latency setting in Mainstage 2 at all, so I can't switch it to off and fix this like I did in Logic.

If anyone has ANY idea how to do this or anything I haven't tried yet that would be amazing. It's very disheating that this strange problem is happening to me and is preventing me from using this almost perfect piece of software, but I cannot perform with the audio distorting 30 seconds after I change a setting. Thank you