Col has hit it on the head, this is why I asked what boost you were running and whether it feels like your cars hitting a limiter. I probably wouldn't be running in excess of 12psi all day anyway, especially not in this hot weather. Your car may be spiking as well, causing the ecu to boost cut but then when your boost falls back it allows it to go. Regardless, the only way to fix your problem is to do one of the things mentioned above, saving you money later will be to buy a pfc or safc at least.
Good Luck, Matt