Do I have to change all the ignition coil packs on a 1993 lexus ls400

 

from 90-97 at least, there are two coils on these cars, one feeding each distributor. They are not coil-on-plug coils.
And I think you generally change them when they fail, which may be never.
I replaced both on my '91 at around 180k miles, while I was chasing another problem. Turns out the new ones run just the same as the originals, so they were still good. Saved them of course.

 

no, just the plugs, wires, and caps and rotors for a tune-up.