2006/206 mystery electrical gremlin

2006/ 206 with 570 hours. Excellent operation and performance history, BUT it has strange happenings, it will randomly go into what I call "limp mode" where it will drop into idle only. It can only be reset by shutting down and re-firing. No codes come up when the PCM computer is attached, so that is no help. I thought it may be a voltage issue, and replaced battery. The alternator is putting out at 14+ volts ( according to my equipment). I have checked and tightened all wires and cables that I can find. I AM AT A LOSS HERE!
If anyone has input I will greatly appreciate it.
Please note this is random, it may not do it, then another time it will kick out 3-4 times in an hour.

There were no code histories, and since it is random, hooking up and riding around until the event occurs is not practical! The dealer mech has way too much going on, and they won't leave that little baby for me to try and troubleshoot further. Can't say that I blame them, I won't loan out my test equipment either.    But you indicate that you believe it to be a fuel pressure issue. Have you experienced this? It has done "it's thing" when the engine is cold so I tended to rule out the electrical pump getting hot ad failing. What has me stymied is that it essentially resets after cycling the keyswitch.