All very good feedback guys. Very much appreciated.
This is the FIRST time ever this car has done anything like this. The only other malfunctions the car has ever had is a broken belt, broken timing chain tensioner, and two failed O2 sensors (at different times).
I've had a fair amount of self-diagnostic experience trying to diagnose a problem with a Ford that I had, so I learned a LOT at that time about all the various ways that the sensors work and how the engine behaves when certain things go wrong...so thankfully I'm not totally in the dark on this one. But, being the first time I've had to troubleshoot on this car, I certainly need some help from some veterans here.
I do have a ODBII plug-in diagnostic module (with the matching Android app called 'Torque') that will spit out real time diagnostic info and engine stats, so I'm hoping that I can get some useful info from it while it's acting up....as well as go out and read any codes that might have been generated (haven't done yet).
If it's the ECU and caps need to be replaced, no problem. I have YEARS of professional level experience working on electronics at the component level and replacing parts. For me, this would be an easy and fun fix.