Fuel delivery/ Vaporlocking issues

I have a 99 S-10 2wd with the 2.2 liter 4 cylinder engine. After I have been driving for 15-20 minutes it will start to cut out/sputter and the motor dies. I typically cant get it to start back up for 20 minutes or so. The temp gauge never goes much above the 210 mark and I cant figure out whats wrong. It typically only does this when the weather is warmer outside. Also, I pull a small trailor and it tends to do it more often when I am pulling that. This problem doesn't occur everytime I drive it, just occasionally. I replaced the fuel filter and ran bg44k through the system but the problem hasn't gone away. Ive had the vehicle for about two years and it has only started doing this in the past month or two. I want to think its the fuel pump but when its not acting up it runs flawlessy. Any advice would be greatly appreciated.
Thanks
Andy

It is not a vapor lock.
Vapor lock went out of style years ago with the carb,s.
Fuel pressure and spark needs to be checked when it no starts.
MT