Engine slight "shiver" at idle- normal?

[fixkick]

its not a problem, really ,just sounds odd.

I do the 2 troublesome parts at once.
maybe your EGR leaks a bit and the ISC goes nuts trying to correct it, but in all cases it will get worse. the muck never decrease, only gets worse. (adds)

The ISC unbolts ,pretty easy, sure it will leak some AF antifreeze, so plug lines quick, cold radiator.
the EGR bolts 6mm thread love to stick, use very gentle force, there, like 7 ft/lbs max, use penetrating oil.first,
this EGR clean is a 50k, service point, if you get some anti-seize lube on the threads it will be child play , hence forth. (do that to both valves)

here is a video of the ISC, head that sound its a happy ISC, snappy.
http://www.fixkick.com/videos/FLV-all/showtime.html#ISC

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happy trails !!!