end of tether time

[gsxrboy]

i have a 98 v70 t5, with remap, full exhaust etc, i have an intermittent boost problem. one day i will have 18psi, the next time i drive it drops to 10, it might stay like that for a couple of days then goes back to 18psi.
I have fitted an mbc and a forge dump valve so in essence the ecu has no control over boost levels.
Would a dodgy 02 sensor or connection cause boost loss due to the ecu adjusting the fuelling? i have had a code flash up on the torque app indicating front 02 sensor fault (p0137) but at the time i had full boost.
i have checked every hose and pipe, checked and tightened every hose clamp, i don't believe i have a boost leak.
any ideas?

[shaun850]

Maybe a sticking boost solenoid?

[gsxrboy]

Maybe a sticking boost solenoid?

i have an mbc which replaced the tcv

[Rnash2002]

Maybe a actuator problem or wastgate sticking.

[mitchyboy01]

I'd start with actuator