Spark plug leads are an often neglected item. They do go off with time and ideally, should be changed yearly. Of course, this only applies to petrol powered motors.... It's an easy exercise on the 3F and somewhat more involved on the 1FZ. The later requiring the removal of the plug lead cover plates on the top of the rocker cover and those fiddly plug lead ends.
A note from Andrew Roane:
Last week I replaced my stock plug wires (the original wires were dated 7/89) with Bosch 7mm High Temprature Silicone Spark Plug Wires.
I usually go to the Mountains once a month and went this weekend, same route same speed as before I replaced the wires. The new wires made a huge improvement. On long uphills the '91 Cruiser just went right up without changing to third gear. I don't no if my original wires were worn out or not making a proper connection but it is like a new truck. I wish I would have done this a when I originally bought the Cruiser in March '95. Hell, I could even set the Cruise Control. The time in seconds from 75 to 85 mph is also greatly increased. I was passing people on the two lane that I have never attempted before.
The new wires might not help all Cruiser owners but for $31.50 it is sure worth a try. It takes about 20 minutes to install.
And no I do not work for Bosch.