Upper hose is collapsing!

Thanks for all the advice guys. I am going to stop on the way home today & get another new cap to try & a 160 thermostat. My father told me to go without a stat but he is old school & from what I am reading online it is a bad idea to go with no stat at all so maybe a lower temp one will help with my vapor locking.
Any advice or tips on flushing out the motor? I am going to get a couple cans of whatever at the parts store & just follow the instructions. It is a brand new radiator so the engine itself is my real concern. Thanks