no mileage state, nor from last full tune.
it needs a tuneup this decade.
oldest story on earth (cars) (bad spark)
no ignition parts (high voltage) last the life of any engine,. 300k+
so we do what is called a full tuneup at about 60,000 miles.
also called doing the 60k service point list.
open glove box, take out operators guide, yes, really
turn to the 60k page. bingo.
high voltage breaks down all the insulation,
even your power company must do this. or BOOM,
Have 2 dead friends from BOOM. 17kv distra. systems.
no engine stated so can not be specific.
my guess, is tghis.
The third-generation 3S-GE was produced from 1994 to 1999.
1996 is a big change year, OBD2
and from Distributor spark to none, at Aug, 1996 they swiched
to the DIS system. with a wasted spark coil pack only.
replace the HV wires, and spark plugs.
if the scan tool shows, P030x errors. fix X
if x is 2 cylinders it might be a bad coil pack,(last thing to replace)
there are 3 spark systems , at this evolution
Distrubutor with internal coil.
wasted spark coil under TB, with 4 HV wires.
and coil over plugs, later, called COPS, 4 coils.
yours may be wasted spark system with 4 HV wires,. replace them.
show a photo of the engine, and i can ID it. in 1 second.