 Here is a basic structure of the Python code using PyAEDT library for the given task. Please note that this is a simplified version and might need adjustments based on your specific project requirements.

```python
import pyAEDT as aedt
import os
import shutil

# Set up project files and paths
project_name = "my_pcb_analysis"
project_path = os.path.join(".", project_name)
temp_project_path = os.path.join(project_path, "temp")
edb_path = os.path.join(temp_project_path, f"{project_name}.edb")
q3d_path = os.path.join(temp_project_path, f"{project_name}.q3d")

# Download project file
aedt.check_and_download_file("https://example.com/my_project.prj", temp_project_path)

# Create temporary project directory
os.makedirs(temp_project_path, exist_ok=True)

# Open EDB project
aedt.clean_cache_and_files()
aedt.get_version_and_release()
edb = aedt.open_edb(edb_path)

# Create cutout on selected nets and export to Q3D
# (This part requires specific net selection and cutout parameters)

# Identify pin locations on the components
# (This part requires specific component selection and pin identification)

# Append Z elevation

# Save and close the EDB
edb.save()
edb.close()

# Open it in Hfss 3D Layout to generate the 3D model
hfss_3d_layout = aedt.launch_hfss_3d_layout(q3d_path)

# Export the layout to Q3D
hfss_3d_layout.export_to_q3d(q3d_path)

# Launch the newly created Q3D project
q3d = aedt.launch_q3d(q3d_path)

# Plot it
q3d.plot()

# Assign sources and sinks on nets using the previously calculated positions
# (This part requires specific net selection and source/sink assignment)

# Create a setup and a frequency sweep from DC to 2GHz

# Analyze the project, compute ACL and ACR solutions

# Plot them

# Release the desktop
q3d.release_desktop()

# Clean up temporary files
shutil.rmtree(temp_project_path)
```