Careful, if you're gonna flush it, there's a proper way to do it. If you don't do it right, you'll get air into the system and air doesn't really do a good job of cooling.
That happened to me, and they had to flush the system multiple times. My temp needle flew off the scale multiple times and it scared the shit outta me. Take it to a respectible shop. They tried to top mine off, but it only got air into the system somehow. But they fixed it for FREE!