2002 Honda Accord idle fluctuates

2002 Honda Accord 56,000. On a cold start the car goes into fast idle mode and after a minute the idle starts to jump between 1,500 rpm and 1,800 rpm. I've been trying to fix this for a year. I've replaced the O2 sensor and PVC valve as you told the another poster to do. I've also replaced the Air Temp sensor (TA), Water Temp sensor (TW). I've stumped the dealership, as they find nothing wrong. I even replaced the fast idle valve and EACV! The engine has been tuned and I have no clue what else to do? After the engine is warm, everything is great and runs really well and car is like new after constantly doing the service on time.