Aveo 2004 ECM Problem

A few days ago I took my Chevrolet Aveo 2004 to the workshop due to a failure.
The engine was shaking, that is, it accelerated even when in Neutral. According to the technician it is because the computer (ECU or ECM) was defective. We tried a new computer and the problem stopped appearing but it no longer accelerated to start it.


Which makes us think it's the computer. The problem is when you want to buy a new computer there are many "versions" that I do not understand and I need your help.


The one in our car has these initials "5H"
Attachment 12122

But wanting to buy on EBay many more initials appear, for example "FH", "PQ" Etc.
Attachment 12123 Attachment 12124

What do these initials mean?

I'd appreciate your help.