Little late but I've promised an update.
After more than week and ~500 miles since applying zip-tie fix to fuel pressure sensor plug I can say that the issue is gone. The vehicle is pleasure to drive - as much as economy car can be, now if only traffic was better.
Visited local junkyard and secured FPS and pigtail (plus other pieces for total of 16$ - better than Internet prices) but for now I'll keep zip-ties - I'm not cutting into the wires unless I have a good reason to.
Responding to the preceding post - spark plugs and spark plug wells looked OK and no oil leak.
Now to sum up the ordeal - I'm not sure who messed up the connector/plug on FPS - could be me, could be repair shops (during unnecessary but suggested repairs they had to disconnect it at more than one occasion). It's quite likely that the issue started due to normal wear (spark plugs/wires/cables) but later on it switched to FPS issue as the connector got damaged. What really sucks is that none of the shops I took the vehicle to was capable of correct diagnostics. Instead they relied on hunch (which is OK if you're an amateur trying to fix your own car "on cheap") and suggested quite pricey repairs (some of which required pulling apart stuff that's better to keep stock).
Lesson learned - take it to the shop only for things that are regular maintenance procedures you can't do at home. Don't really expect finding out the root cause of non-obvious issue (unfortunately you have to live with it or end up paying for nothing).