My T100 with about 79000 miles is getting a little harder to start. Not bad, but it turns probably 5 or 6 revolutions before it starts. I does idle a little rough.
It had a major service at 60,000 which included injection service.

Looking at the ignition set up, I occurs to me that those plug wires would wear out twice as fast on this engine as those on a V6 with six plug wires. On this one it look like the plugs must fire twice each revolution. That would be the equivalent of about 160,000 miles on the wires.

Any other ideas?

If you want to check these plug wires yourself the specifications list says that there should be max 25.0 kOhm per wire. The OEM wires look really skinny but if you buy the set from Toyota you get all three wires cut to length with boots attached and I think they are already mounted to the clips. I didn't test or measure mine but they were only $50 and 10 years old.

The ignition seems pretty reliable on this truck. There was a recent comment by one of the masters about the rarity of failed ignition coils. Your funky start and rough idle could be caused by anything. Drop any codes?

the rough start could be the battery starting to go bad. the rough idle could be the wires or could be the plugs.

I have a set of NGK wires on the way. haven't checked the codes yet. Would it turn on a CEL if it threw a code?

Sometimes. The diagnosis chapter from the 97 manual is here: http://users.757.org/~ken/T/04-Diagnostics.pdf

On the topic of ignition I am having great results with OEM wires and OEM plugs and old coils with 130k miles.

I have not had to troubleshoot any engine problems with my truck yet but in another world where different rules apply my idle problems have always been caused by vacuum leaks which could be anywhere. first test is to remove the oil fill cap and see if the idle is different

Thanks eleet. That is a pretty complete manual for troubleshooting. I'll have to get the codes read. Do you think it is the same for the 3.4l engine?

Oh yea, my idle is a little low too- around 500-550


Where can I get a manual like that one for mine?

I just changed my wires at 10+ years and 90K miles. No signs of trouble but the wires are clearly the weakest link in the 3.4 crossover ignition system. For $50 or so I felt it was reasonable preventive maintenance - at that age time takes over mileage as a wear-out metric, the insulators and conductors in the wires could easily degrade to the point of loss of spark energy. The OEM set is a harness that includes all clips, hangers, etc. and will keep the wires in the proper places away from hot spots, etc.

The V6 is discussed later in the document. It is quite different to the other engine. The easiest way to get this is to buy the Service Manual on paper from Toyota, but forum search will yield additional methods. The document from me is for model year 97, yours could be identical or have minor changes. This is also only one chapter.

Remember that the manuals are no longer written for beginners, the recent Toyota manuals are written to assume that the reader has taken relevant Toyota training. Such was my mention of checking for vacuum leaks. With a low idle speed I think the manual wants you to consider fuel pressure.

Let us know how the aftermarket wires work out. I got more bang from changing the crap autozone plugs from previous owner to the factory specified plugs. No detectable improvement on my vehicle from the wires (I did these several months apart) but I am happy to have new ones & some old rotten rubber gone.

I have had good service from NGK and Denso wires. I think they are OEM for some cars in Japan.

I saw that the manual asks to check fuel pressure several times in the TS chart. I'll do that.

The plugs in mine are OEM with about 18000 miles, from the dealer. They look new.

I've replaced mine at around 90k with Duralast brand, and so far so good. There was a definite increase in engine response after the replacement.

160k on it right now.