2014 Camry with a 2.5 4cyl, automatic.  92,000 mostly highway miles.  Well-maintained.  In the beginning of the summer I took a 2 hour ride to the beach in 95+degree weather.  Before I left for the trip I put some Chevron total fuel system cleaner in it and filled it up.  After the 2 hour ride the car sat for about 20 minutes and when I went to start it, it hesitated for a few seconds severely, turned over and ran really rough for about 15 seconds.  It did it again 2 more times later that day.  Once the 15 seconds were up it ran fine.

I tested the battery and alternator and they were fine.  The next week I drove it to work and no issues.  One day I did a lot small trips and at the end it did it again but no where near as severe and once started there was no roughness like before. 

Took it to my local mechanic and of course he couldn’t reproduce it but did find a small reduction in fuel pressure when starting the engine after it was warmed up.  He suggested cleaning the throttle body and replacing the spark plugs.  He did say that it may not be the plugs but they did have 90K on them so I thought it was a good idea regardless.  He also put fuel injector cleaner in the gas tank.  I also changed the air filter and replaced the battery myself afterwards. 

Now it’s the beginning of Fall and it still is occurring from time to time when the engine is warmed up then off for a short period of time.  Once started it runs fine, I have not acceleration issues and it idles perfect.   

Not sure what to do if anything?  Any suggestions would be appreciated.