Given your description, I flipped through the field guide, thought it over and Dollarbird is a possibility. I haven't spotted one that I could ID for sure, though your description fits a couple of my own observations. The other possibility would be escaped/released Myna as that is rare but you do encounter them.
The Cuckoo are just arriving and in fact I haven't seen or heard one yet so good for you.
Don't feel too bad, I spent a total of five years in Shenyang and never made it out to Dongling. Though in my defense I wasn't seriously birding at that time.
Thunderstorms predicted in Panjin today but so far it has stayed just east of here. Maybe you'll get lucky and it will generate a fall of some migrants for you.