Hi, Sheren and the usual suspects are:
1. Throttle cables improperly adjusted, pinched or need lubrication.
2. Idle adjusting screw needs to be backed off.
4. Air fuel mixture adjusted too lean start with 2 full turns.
5. Intake system air leak.
6. Fast idle choke ramp is not releasing.
7. Broken throttle return spring.
8. Damaged diaphragm or slide.
9. Faulty MAP, TPS, ATS, O2, sensors or wiring/connector.
10. Multiple carburetors not in sync.
Good luck and have a wonderful day.
Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/gregg_c0ec1df182c7330e