p1127 p1426 breaks up under boost

[ogemtakool]

-1998 audi a4 1.8t quattro
-230k miles (second motor at 160k)
-apr chip (test pipe software)
-3 inch turbo back custom exhaust (no cat) (both 02s installed)
-s4 diff and trans
-cone filter mounted onto maf
-recently removed bov(hks ssqV) and swapped to forge diverter valve without recirculation (may be my problem)
-replaced coil packs with new oem
-replaced maf new oem
-replaced spark plugs new
-pressure tested: holds pressure but slowly drops (small leak from diverter valve) (pressure leaks from under oil cap and dip stick pops out so have to push down on both to test (is this normal?))
-have a boost guage car runs fine under 0 lbs of boost.
-as soon as boost goes over 0 psi starts breaking up
-purge valve not clicking but tested wire from ecu to 7v and tested valve to be 28 ohm
-02 sensors are responding with similar readings
-02 sensors tested (Set the multimeter to read resistance (ohms) and measure between pins 1 and 2. both -tested below 20 ohms)
-tried reversing diverter valve no difference
-current codes that are running are
-car stalls at idle pretty frequently
-when rps are high takes forever for rpm's to drop
-p1127 Fuel Trim: Bank 1 (Mult): System too Rich
-p1426 17834 Tank breather valve -N80 Open circuit


i am stumped please help
im thinking about swapping back in the BOV

[shoemaker617]

spark plugs gapped properly, is it a stock turbo? Do you have the correct injectors?

[Crispy222]

ICM

Since you removed the stock air box, there is less air flow over the heat sink to keep it from melting down inside.