the stereo turns on and off and the guages flicker on 1990 GMC 1500 Pickup

the stereo will play fine and then the stereo starts to shut off and the guages start to flicker,, i have cleaned up the terminals on the battery and checked the ground and all seems to be fine,, the cd player is hooked up to a amp and sum

Asked by for the 1990 GMC 1500 Pickup
Check charging system and battery! If not equiped to do so have them checked. Battery needs to be load tested and cells read with a hydrometer to be sure, cant just say well it cranks ok! A battery that has just one weak cell can crank the engine fine but overwork the alternator. So have them both TESTED! How are you sending power to amp? Maybe unhook that stuff to see if it helps.
i did charge the battery and it seemed to hold a charge, it is only 10 months old, it seemed to go away for about 15 minutes or so and then the stereo started to turn on and off and some of the gauges started to flicker again, i disconnected the amp with the rca jacks so the sub wasn't working however that didn't resolve the problem,, i guess i should find the tool to remove the aftermarket cd player and disconnect the power at the sourse to see if that helps?