The reason your game is crashing after changing the item ID's using cheat engine is because that's only the clients value, for the sprite.
The server side also keeps track of what's in your inventory and when it notices that the values don't match, the game crashes.
Don't waste your time and/or risk your account(s) using cheat engine to dupe. I've spent countless hours messing around with
cheat engine duping methods and was only able to make a dupe happen once, and then never re-create it.
If you insist on wasting your time trying to dupe using cheat engine, I will tell you this one tip:
The only weakness in the server/client checkups is in the trading screen, so you will need a partner to figure it out.