The poor running could well be the timing that is off, no matter what it is definitely worth to get verified!
Mine does not have EGT, but I think that I have read about a connection between the error code and timing issues on alfabb.com
Also, I have tried driving my Q4 with the timing 2 notches off, that was not nice! So get the timing checked asap.
1994 Alfa Romeo 164 Q4 Proteo Rosso 530.000km
1989 Lancia Thema 8.32 Verde Indy 260.000km
2015 Alfa Romeo 4C Rosso Competizione 45.000km