The electronic control module (ECM). Can a 37820-RP3-A53 be substituted for a 37820-RP3-307?

What is your question?

The car keeps stalling if going under 50mph (and occasionally at higher speeds). We were told the ECM needs replacing. Since Honda discontinued the Fit, we need to locate/ purchase our own part. The 307 replaced the A53 a while back, and we have gotten conflicting advice about using the A53. Is there any reason we shouldn't use the A53 in the repair( since it is about $900 cheaper than the 307)?

How long has your 2009 Honda Fit had this problem?

months