Help needed on a 2001 Kia sportage

[smosmo]

I have a 2001 KIA Sportage,4dr,4wd.I have had the timing chain belt changed,new alternator,new fuel pump,new O2 sensor,new fan for the heater and a new fuel gauge installed.Now,when it's over 60degrees outside,it starts,drives fine for a liitle while,then it starts choking and just shuts down. If I wait about an hour or so it will start back up,but depending on the outside temp,doesn't stay on for long.I have told this to my mechanic and he just acts like I have no idea what I'm talking about.I also called the KIA dealership,and their service tech,just kinda blew it off! Can ANYONE help me PLEASE???