Leads????????

[snozzau]

Guys,
Dont want to flog a dead horse on this one but is there a set time that plug leads should be replaced at?
My AU3 XR6 has 140000 on the clock,can be hard to start,idles a bit rough and is fairly thirsty.
Injectors have just been cleaned,plugs replaced,fuel filter looks brand new.
I am looking at a set of jmm extractors and might go with their leads as well.
All ideas and opinions welcome.
Cheers,
Snoz