i need help when i'm at a stop light and the car is idling, the idle would drop rom 750 and dip down to 500 and than back up to 750 for 5 seconds than drop again. When i start to drive off than it's fine but only happen when i'm idling in gear . it's an auto btw. i'm thinking ignition coil but don't know how to use an ohm meter, to check the ignition coil. any suggestions as to what it might be? please help

 

Check your IACV. Mine fluctuates a lot when the IACV is set too low. Adjust it with a screwdriver and see if this changes it. Might just be starving for air at idle in gear when the AC comes on and off.

 

Take some time and clean the TB and IACV as well. That will make a huge difference in how the car will idle

-matt