I think that's a really *expletive deleted* idea. Something has changed in the hardware, let's just fiddle the software to make it all better. What could possibly go wrong

The map is close enough (by my reckoning at least) that it really shouldn't need 20% more fuel added to make it work unless you've fitted 440cc injectors and completely forgotten about it. Saying that Itchy-san turned in some good numbers. Has he been alone with your car at any time

Assuming the map hasn't been corrupted and there isn't a doolally sensor creating bad corrections there is probably a fuel injection problem. It might be pump or injectors or anything in the wiring
NB I say probably because it's not impossible that there was a problem when it was mapped which has now gone away - stuck FPR, blocked return line etc etc
However, that said I don't honestly know what else you can do. You're missing essential data that would help diagnose the problem. All you needed was rail pressure when it was mapped

So I would correct the map and then make damn sure I was keeping a very close eye on the AFR to see if it is still drifting. Given the situation I'd try and get some logging on rail pressure to try and rule out a fuel pump going down under load. I'd also be trying my best to get some general logging done to try and rule out Duff sensors
Mmmmmmmm, Duff, aaarghhhhhh