Z axis Stepper motors not working correctly
So after 5 days of trouble shooting, Bob-the-Kuhn over on the marlin github forum solved it for, anyone else who faces the same issue can head over to github for my solutions.
https://github.com/MarlinFirmware/Marlin/issues/9287#issuecomment-359428147
Conversation from link:

Bob-the-Kun:
Problem does not follow the driver. Problem does not follow the
steppers.
I'm thinking that the Z socket has a problem. Sounds like an open/poor
contact.
Try bending the DIRECTION lead on the Z driver a little and see if the
problem disappears. It's one of the corner pins. Sometimes it's called
DIR. If your driver's pins aren't labeled then bend all four corner
pins a little.
Another option is to move the Z function to the E1 socket. Replace
your pins_RAMPS.h file with this one. pins_RAMPS.zip
FYI - if this really is a hardware problem then it's the second RAMPS
hardware problem within a week. Most unusual.
Post reply:
Yes the socket I am now assuming is just broken (not sure what exactly
but possibly one of the connections), After using for pins_RAMPS file
and changed the motors back to series and connected to the E1 slot I
successful got the printer to work!!! Thank you very much Z axis is
working as I would expect! I am now calibrating the printer as it
definitely needs it.