[parbs]

Hello everyone,
i have a gy6 150cc scooter issue. I thought someone might be able to help.
The scooter starts and runs great for the first 15 minutes. It idles about 1500-1900rpm. Throttle and carb is responsive.
After it warns up, it begins to run rough and backfires. It will run seemingly okay a idle. However, i notice at low idle, the rpm reads about 6000. I know this is not accurate. After cooling down, 20 minutes later, it runs excellent again.
what have i done to resolve the issue?
1. change plug with new
2. tightened exhaust to ensure no leaks
3. investigated any vacuum leaks. none found
4. replace carburetor
5. tried changing cdi box, no luck
6. checked and replaced fuel filter
7. left open gas tank lid thinking vent hose may have been blocked, no luck
8. Replaced spark plug wire, no luck

any suggestions? many thanks