I had a few years when I'd get an intermittent transmission fault. The display would loose the 'D', replaced by a '-'. I'd get a check engine warning light, and my odb2 would report transmission control unit communications failure. The car would feel like it was in too high a gear, lacking in power....

actuator diaphram is ripped, replace. re-set the wastegate preload.
it doesn't look like a huge leak.

Whoa, now we're getting somewhere. Sounds like I might need to take it somewhere to have the preload set properly. its very simple, actuator rod has a threaded clevis that fits over the wastegate pin, you adjust it so it holds the gate closed with engine off, just slight tension to prevent the gate...

Make the wastegate clevis 1/8 inch short of reaching the gate actuator pin..., pull the actuator rod out and slip it on, done.
The slight tension holds it closed as it builds boost, until the ECM tells it to blow off excess pressure.