98 Regal ls/P0507

My 98 has 460,000 km on it.
I get obd2 code of po507(high idle detected)

At first My idle would go down to about 400 rpm which caused it to stall.
I changed the pcv valve and the map sensor(because I busted the map doing this).
When I started it up it idled at 500 rpm.(slow but working)
I drive a lot and after about 3 hours the idle changed to 600 rpm(normal).
After 6 hours the idle goes up to 1500 rpm and the po507 code will pop up.
I know that if I turn the key to the on postion for 10 seconds then turn it off for 5 seconda it resets the IACV.
I do this and all is back to normal for about 3-8 miles.

My Q is "is this an indicator that my idle air control valve is shot or something else?"

Cheers
Stripe

Could be a flaky IAC. But remove the IAC first and clean the pintle with carb or throttle body spray cleaner first. Secured by two Torx T20 screws. Then lube pintle with silicone spray. Then clean the seat at the throttle body where the IAC mounts. The TB accumulates alot of carbon over the years or based on your accumulated mileage if it has not been cleaned out.

Did you reremember to remove and transfer the lower PCV valve o-ring from the old one when you changed it?