Maybe you should try using Mode 1.
It is the same as Mode 3 but it only sends 10bits (1 start bit, 8bits of data, 1 stop bit)while mode 3 sends an additional bit TB8.

If you persist on using Mode 3 then you should also send the right parity bit (TB8) or tell the terminal program to ignore the parity bit if this is possible.

Panos Kenterlis
Computer Engineer
Greece