Just curious
Well I know that when you do a tune-up you suppose to change everything.
But could anything bad happen from just getting new spark plugs, dizzy cap
and rotor but using the original spark plug wires? I'm asking this because
my car only has 84,000 and it's a 98'.

you would be surprised how much of a difference those wires can make. i use to do a tune up every other oil change just to do it, but i only changed the plug wires twice in the last 8 years. i felt a huge seat of the pants gain from replacing the wires. the engine also seemed to idle much better.

Well would I see an improvement with just replacing the spark plugs, cap and
rotor? I will replace the wires just not now because of funds.

i'm sure you will. i felt no difference when i did it without the wires though. it wouldn't hurt anything to leave the wires off for now. also, don't forget about the PCV valve. i think they are about $5 from Nissan.