Section 175 (Engine Controls - Tests W/O Codes): Symptoms: Surges

WARNING: This page is about a different car, the 1995 Mercury Villager. However, it is still accessible from the selected car via links, so may be relevant.

Check for vacuum leaks.
Check idle air control systems. See appropriate SYSTEM/COMPONENT TESTS article.
Check fuel delivery system. See SYSTEM/COMPONENT TESTS article.
Check EGR system. See SYSTEM/COMPONENT TESTS article.
Check EVAP system. See SYSTEM/COMPONENT TESTS article.