Weird Idle issue?

[shipkiller]

In addition to what modmonster2008 said, if there is a small amount air in the system, often the rest of the coolant system may act normal, but the bypass lines and smaller lines may have a bubble in them... So if there is not continuous coolant running through the ISCV, so that the coolant temp running through the ISCV housing is not consistent with the rest of the coolant in the system, it will affect it's ability to work correctly, thereby having too high / too low or erratic idle...

Oh thanks, that might explain my idle issue too (I hear bubbling when I put on the heater and I rev a bit the engine since I replaced the coolant, gotta fix that)