P0507 Idle Air Control Error After 2003 Nissan Sentra Spec V Service at 110,644 Miles

Good morning, I recently took my 2003 Nissan Sentra Spec V (110,644 miles) to a service shop for its 100K maintenance. The work performed included: - Spark plug replacement - Valve cover gasket replacement - Air filter replacement - Brake fluid flush - Complete cooling system flush - Fuel save analysis - Engine oil service - Brake cleaning - Coolant and treatment refill - Fuel injector treatment After leaving the shop, I noticed a significant change in idle behavior: the car would idle between 1500–1800 RPM instead of its normal range of 750–1000 RPM. It also started hard and would shut off with a rattling sound. After driving approximately 75 miles, the check engine light activated. I took it to Pep Boys, where they diagnosed the issue as P0507 — Idle Air Control (IAC) System RPM Higher Than Expected. I explained that this occurred after the service was completed. The technician reset the code and advised me to return if it returned within 100 miles of driving. Unfortunately, the code reappeared within less than 20 miles. Before returning to the mechanic, I’d like to understand: 1. Could any of the services listed above have caused or triggered this P0507 error? 2. During the service, did they work on components that might affect the idle control system, such as: - A faulty electronic throttle solenoid (e.g., a new throttle body installed) - Vacuum leaks in intake tubing downstream of the throttle body - PCV system leaks? My car was running perfectly before service. Now it’s unreliable and I’ve spent $850 on repairs with no resolution. As a non-technical user, I’m concerned I may have been misled. I’d appreciate any insights to help me communicate effectively when I speak with the mechanic tomorrow. Thank you for your help.