Happened to me once and I put in 2 bottles of heavy duty Lucas fuel injector cleaner and drove it until the misfire stopped. Then I filled up with some 93 octane and another bottle of Lucas. Problem never came back.
First of all, you probably didn't need to flip your drag link... You need to raise the track bar to get it parallel to it now.
Secondly, get it out of that shop because they obviously don't know what the fuck they're doing.