punch1001bd and 4 mtx thunder8000 12s

It sounds like you have the gain set wrong...its not a volume control. Half way up can easily be pushing your amp past its limits.

To set gain with a digital multi meter you will need a test tone disc with any test tone between 40 and 50 hz recorded at 0db. Then follow DYohn's directions on setting amp gain with a digital multi meter:

"Voltage = square root (Watts times Ohms).  400 X 4 = 1600, square root of this = 40

So if your load is 4 ohms, your amplifier has to produce 40 volts to be at 400 watts. 

Set amp gain at minimum.  Wear hearing protection.  Start the vehicle.  Play an appropriate test tone from your HU (is this a subwoofer?  Try something between 50-70Hz.)  Turn up volume on HU until you can detect the tone has changed or gone "shrill" or "flat."  This is the distortion point on your HU and is the MAX volume you cannot exceed without causing possible speaker damage.  Back off the volume until the tone is clear again.  Memorize this volume setting.  Turn off the HU and the vehicle.  Disconnect your subwoofer from the amp.  Connect your DMM set to AC Volts with the positive meter input connected to the + speaker output and negative to -.  Start the car and turn the HU back on.  Play the same tone and turn the volume up to your earlier memorized setting.  Slowly turn up the gain on your amplifier until your meter indicates 40 volts AC.  This is the max gain setting to match the HU output.  Mark it with a sharpie.  Leave it there and never touch it again.  Disconenct your meter.  Turn off the HU and the vehicle, reconnect your subwoofer to the amp.  Fire it up and see how it sounds on your music.  If the bass is overwhelming the mains, you can back the gain setting DOWN to balance the system, but NEVER turn it up past the point you set with your meter."

https://www.the12volt.com/installbay/forum_posts.asp?tid=50672&PN=2

You need to set your gain properly. It is not a volume control. What kind of hu are you using? We need to know this in order to help you out.

You can wire your subs for 8 or 2 ohms. I would wire them for 2 ohms to get the most out of your amp:

From what I have heard those subs are power hungry. If someone was expecting more out of them with 250 watts going to each and cranked the gain on the amp (or set it to half way) what would happen is probobly what you are experiencing. The amp is being pushed to hard and is cutting out. You could also be experiencing a bad ground. Those RF amps need a good ground to work well.

Are your subs in a sealed box? If you would like to keep the same amp but get more volume out of them then I would switch to a ported instead.