Engine Runs Rough At Idle

Turn ignition switch to ON position. Using scan tool, select INJxF PIDs from PID/DATA MONITOR & RECORD menu. There is one INJxF PID available for each engine cylinder, and the "x" indicates the appropriate injector number (1-10). AllINJxF PIDs should indicate NO (no fault). If any INJxF PID value indicates YES, an injector fault exists. Go to TEST HA, step 60)  (Natural Gas models), or go to TEST H, step 56)  (all others) under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V - GASOLINE & NGV article.