Outer Limits 4x4 Board

Hi, I have a G16A MPI in my sierra and I have been trying to tuning it (haltech E6X). But recently I noticed cylinder 1 is also very rich (as in black on spark plug) while the other 3 are fine. I have swapped the injectors around with no luck. Just swapped the return line with the breather line from fuel tank and that didn’t help.

So I am at my wits end now, anyone have any idea on the problem.

Would a dodgy fuel pressure regulator cause it? Any help would be great.

check the psi the fuel is coming in at and get ti tuned on a dyno.