Toyota Repair: 99 Toyota Camry Idle Problem, toyota camry, customer service representative

Question
A few months ago I purchased a 99 Camry 4cyl, with 43000 miles from a large Toyota dealership. When the car is warm to hot , it will sometimes have an erratic idle upon start up. If I wait a few moments it will smooth out, if I give it gas it will smooth out and run at a spec idle of about 650 rpm.When it idles erraticly it will race between 500 & 1000 rpm ( I can hear it & see it on the tach). It does not feel like it's going to die. I got a few different opinions and all thought it to be the IAC. The dealership would do nothing until they could duplicate the issue. A week ago they changed the IAC (or said they did , I did not see the used IAC and the service writer called it an interal invoice). It just began to do the same thing again. Other than this the car drives and feels great. I'm getting very tired of dealing with this issue.The Camry has now been  to the service department 5 times in 6 weeks, all documented, what should I do. They have been kind enough to service the car without charge because the problem has been there since I purchased the car, but I'm scared that they will start to charge if the issue continues. I have a limited power train warranty ( certified used car )which does not cover this issue.   Thank you for your help.  

Answer
Since it is a certified used car the warranty coverage on major components is up to 100,000 miles, I'm not sure what the problem is but ISC, idle speed control valves, are a common problem, you may want to consider having another toyota dealer diagnose the problems because the one you are going to doesn't seem to be knowledgable enough to solve the problem, the warranty is in effect no matter what dealer you visit. One other option is to request for the dealer to buy the car back and offer you another deal on another car, it may be time to call the customer service representative at the dealer and let them know about the problem and demand that they fix this or just take the car back. Have you tried talking to the Service Manager, a certified used car is supposed to be in perfect condition and you should not have to put up with this,if the service manager is of no help stop talking to the people in the service department and start talking to the customer service people at the dealer.