Process

I recently got HPTuners on my car and had dialed in the tune almost perfectly so far. It hit a perfect 23.5 PSI and everything was almost 100% done. Now, the setup I had was an HKS SSQV that was recirculated back to the intake (so it wouldn't cause any problems). I recently got rid of it for a Forge BPV, but ever since installing the Forge, my boost is a problem.

The turbo will spool perfectly fine till about 7-8 PSI, takes awhile to get to around 15, and then will shoot back down to 8 once it gets around 10-15 psi. Does not go anywhere near my typical 23.

Things I've tried:
Tested wastegate for being stuck and verified proper preload on the adjustment rod
Checked ALL vaccuum lines, and done multiple boost leak tests before and after the turbo. holds 26 PSI just fine
Forge BPV has been rebuilt, leak tested, does not leak under 26 PSI. I have tried both green and yellow springs.
Turbo spins freely and has absolutely no shaft play. No oil being burned or in the charge pipes either
MAP sensors are brand new GMS1 sensors with ZZP harnesses
I have run the BPV directly to the intake manifold with no change other than slight flutter when shifting in vaccuum
MAF is brand new
Lambda under full throttle is still perfect despite the major boost loss

Any suggestions? My only other thought is the wastegate solenoid but I can't seem to find a new one for under 150 dollars,so is there a way to possibly test the wastegate actuator without removing it? If I were to unplug it, what would happen? Thanks.