When the truck is at idle, it feels like there is an imbalance in the engine. Anyone else have this problem? I took a look at the harmonic balancer and it, too, appears to be shaking. Do these things go bad?

 

when's the last time you did a tune up on your truck, sounds like could be plugs or wires. Are you getting any kind of codes. As for the harmonic balancer they dont go bad unless there damaged. Also more info on your ride, 3.4 im sure, but mileage, is it s/c, any mods you've done. This will help out

 

About 120K miles. The truck is completely stock SR5 V6 model. Not sure of the last time a tuneup was done, but the truck has been going through the Toyota scheduled maintenance since new. I will check my records tonight to see when a tuneup was done last.

 

something else to try is either pull it in your garage if its dark, or wait untill night time, start the truck with the hood up, get out and see if any of the wires are arching.

 

One thing to note is that we're having an issue with starting the truck, which may be related....not sure.

https://www.yotatech.com/forums/f16/97-4runner-problems-starting-61649/