Since you have already used the sealant, monitor the situation for a few days first. If the coolant level at both radiator and reserve tank remains unchanged after a few days of driving, there should be no problem with the head gasket.
The idling could be due to other faults. After cleaning the IAAC, was the idling speed adjusted correctly?
If the problem persists after the cooling system has been confirmed to be ok, test the compression. If there are much difference between cylinders, it could be due to valve clearances.
I do not have the name of the chemicals used for testing head gaskets. At parts outlets, tell them the type used to test for presence of carbon in the cooling system.
Personally I have not used any because I have the required equipments to test for bad gaskets.
Friday, June 26th, 2009 AT 8:12 AM