top favoret is allways plugs, then you look at th eengine at night if you see blue flashes round the leads you need new leads. if still dose dizzy cap and rotor arm.
TBH often best off just biteing the bullet and wanging the lot on. my 16v got given the whole lot when i was putting it in, din't know how old any of it was and din't look fully optimal.
IMO dizzzy cap and rotorarm should be changed the same time as leads anyway. plugs normaly get changed every other oil change
