B5_aeb1.8t_stephen

So first off I will start with saying this started with me replacing my downpipe, I noticed it was cracked about 2/3 around the flange. Car did not have this issue prior to replacing the downpipe. After I replaced the downpipe my car under boost and or giving it any slight throttle under 2800 rpms it misfires really bad and the a/f will not go below 13.7 no matter how much throttle you give it, most of the time it will creep to 16 or 17 a/f if I keep the throttle steady under boost. After 2800 rpm the car get plenty of fuel and a/f are fine.
Also when I let off the throttle car goes rich before it goes lean, also happened after replacing the downpipe
Things I have tried to fix issue
smoked the car for boost/vacuum leak which none were found.
New fuel filter
New maf sensor which did nothing
Swapped out coils with ones that were working
new air intake temp sensor

1999 A4 1.8t (aeb cable throttle)
220k miles
united stage 3
630cc Siemens injectors
vr6 maf housing
f21 frankenturbo
bosch 044 fuel pump
adjustable fpr 3 bar currently
Aem wideband
2.0tfsi coil pack conversion/ icm delete
ngk bkr7e gapped to .40
3" downpipe no cat to 2.5" exhaust
n75 with NBC
deleted PVC has catch can off crankcase breather vented to atmosphere .