I replaced my original ECM with a different serial# of a unit I bought off eBay.
Now, my car starts and runs (not before), but now it idles at 2500 rpm for at least 20 minutes each time I start it.
Once the rpms go back down to normal, it idles from intermittently from 500-1000 rpms on its own.
I have misplaced the original ECM so I don't have my serial number, but had seen online that I can provide vehicle information to get a correct part match.

Try calling your local Honda parts department.