2011 Chevy Cruze 1.4L Turbo P0229 Code: Turbo Under Boost Symptoms and Fixes

My 2011 Chevrolet Cruze 1.4L Turbo is experiencing intermittent shudder at idle and sudden surging when accelerating, especially on hills or during passing. This behavior has persisted for over a year without any prior trouble codes being detected. Today, I retrieved P0229 (Turbocharger Under Boost) and P0300 (Random Misfire) using my MaxiMUS 2.0 scan tool. Previously, the car only showed symptoms—no stored fault codes until now. The issue has worsened over time. While I've replaced all spark plugs, tested the coil pack and fuel injectors, and ruled out vacuum leaks, no faults were found in these components. Fuel pressure is within normal range as well. A recent incident revealed a crack in the thermostat housing, which caused overheating and triggered an A/C shutdown. This event also resulted in the storage of both the P0229 and P0300 codes. I believe the misfire (P0300) is directly linked to the under-boost condition (P022 as it's a common symptom). I suspect the root cause lies within the turbocharger or its pressure sensor, but I'm hesitant to replace parts without confirmation. As this issue has become increasingly noticeable—especially during normal driving—I’m seeking advice from others who have faced similar problems. Any insights into potential fixes or diagnostic steps would be greatly appreciated. This is my wife’s car and she's noticed the symptoms too, though she only reported it when the behavior became severe enough to notice. I'm looking for a reliable, cost-effective solution before replacing expensive components.