The idle speed of Chang 'an Star van is unstable. The throttle, idle motor and spark plug have all been changed. Idle speed sometimes rises or falls during driving. What happened?

There is a vacuum tube under your throttle. Are you connected? There is also a wrong connection between the knock sensor and the throttle seat sensor. Then change the air pressure sensor. Check whether the intake branch pipe leaks air, check whether the exhaust check valve is damaged (easily damaged) and whether the carbon tube connecting pipe under the throttle valve is inserted correctly. There is also whether the vacuum tube of the booster is damaged. However, some Chang 'an cars are such a common problem. Can't find anything wrong. I can't help it This is the only way. I hope I can help you.