Wait a minute. Now I'm confused. First, you have a code 44 (lean O2), BLM's pegged at the upper limit of 160, and black smoke.
Now you're telling me you have exactly the opposite? Code 45 (rich O2), BLM's pegged at the lower limit of 90.???
Is this like musical chairs with symptoms, or guess my problem.
There's got to be something really wierd to send the car from one extreme to the other with no explanation. What changed?
Wastegate can't cause either of your problems.
BTW, the reason I run two wastegate solenoids, is because I run an electronic controller (Boost Command). The normal spread of adjustment for one solenoid is between 5-7# from no bleed to max bleed (just an internal limitation because it can only bleed so much air).
Adding the second solenoid allows for more boost to be bled off, thereby increasing the min to max boost adjustability range, now, closer to 10# from min to max.