hello
do you reckon this cable is too loose?
the book says the deflection should be 10-12mm- does it mean the total movement up and down or only down as in drive belts?

 

Looks OK to me.

The real thing is there has to be enough slack, to ensure the throttle is completely closed when your foot is off the accelerator pedal. That's for the idle-control system to work properly. If you tighten the cable so there's very little slack, then things heat up when driving and the cable holds the throttle open slightly & that messes things up.

Besides, if you tighten the cable too much, it can run out of travel before the pedal hits the stop. Then you can bend things if you press the pedal all the way down.