Performance issues in 90 degree plus weather

No warning indicators present. Not sure how to determine fuel psi. The first time that I took it in, diagnostic testing was done, but nothing was found. Obviously, something has to be wrong. Concerned about taking long trips in 90+ degree weather now. Have called dealership for service once again. Could the fuel injector be the culprit? Could getting bad gasoline cause this problem? Thanks for your quick response. I appreciate any information that I can gather before taking my QX in for service.

It would appear that it is more likely to be a fuel problem (likely wouldnt store any diagnostic faults) only because it's very intermittent but it also could be an electrical malfunction. I would highly recommend taking detailed notes in writing and giving it to the service advisor at the service station. I would highly recommend that you allow a technician to take it home if required so vehicle can hopefully duplicate the exact condition in hopes to replicate. Also please send me vehicle vin# & mileage. So i can do one more piece of do diligence.