standard transmission triggers check engine light

Has anyone ever heard of this??

• If I allow my rpms to go over approximately 2300 rpms when shifting my 2004 Chevy Aveo triggers the check engine light with a p0300 code (miscellaneous misfire).
• Several emission fails.

* Compression is all good, plugs Changed

( with maker specific plugs!) Many other repairs also.

Mechanic found rpms were triggering light.

He carefully drove to emissions and was able to get a pass. But he's got no idea what the fix is. Of course after first time I drove it light came back on.

Suggestions PLEASE!