I rebuild my engine and everything is good, the engine has good compression. But when the car warm up and I turned off and turned back on it won’t pass 3,500 rpms.
So I don’t know if the computer or something else
When I plug the air flow sensor the rpms goes up and down from 2,500 to 1,000 rpms but when I unplug it, it’s stays on 2,000 rpms like it normally would do.

 

Scan it for fault codes.

 

Dirty SSV valve maybe or maybe the vacuum switch on it is going bad