No idea if the flow control is compatible with the TAZ, I don’t know that feature.
Ah, I just found out that Simplify3d wasn’t supporting checksums at all until this month - incredible it’s possible to sell software lacking essential functions for that money… Try to check “Include line numbers and checksums” in your screenshot. That should heal your wired moves, maybe even the other things.
I would recommend to do a comparison to another host software. Get Pronterface, save the gcode created in Simplify3D, open it with Pronterface and print from there. First reason to do this: I know Pronterface will make the errors visible for you but I’m not shure for Simplify. Second, Pronterface is solid software, so we can make shure if Simplify has a bug causing this.
The pressure control adds load to the CPU, that’s why it is harder for the printer to keep up with every sent char. But normaly, there shouldn’t be a single error that’s why I think it could be a bug in Simplify…