Which do I replace, amp or speakers?

I have a 2200 watt amp, and two 1100w speakers, the speakers are 300 rms. I have a 2 farad capacitor, my power cables are 4 gauge, and the speakerwire is 8 gauge. The speakers will "clip" after a few minutes, and not produce any sound from my subs for a few more minutes, then turn back on. So, is the problem my amp, or my speakers? I only have enough money to replace one, and don't want to get it wrong, all the techs I go to want to charge for troubleshooting, and won't give me an answer