Engine vibrations post EFI swap (@ idle only)

Bear with me on this one.

I'm getting a strange slight vibration at idle (which is fine BTW). Acceleration from a stop or getting on a freeway on-ramp is fine, as is steady cruising. I've so far done the following:

Replaced engine and transmission mounts.
Checked all vacuum hose connections.
Checked spark plug wires and caps/boots (plugs were changed at the same time as the injectors, early last month).
Cleaned MAF sensor & throttle body.
Ensured that I didn't switch the coolant and vacuum lines to the TB.
Did an ATF drain and fill (fluid was fine, not brown or burnt-smelling).
Replaced the rubber donuts that the exhaust system hangs from except for the forward ones, because they're a bitch to reach.

The engine currently stands at 205k miles and while I know that I should check the valve clearances (my next job as soon as weather and work conditions allow), I'm aware that the valve train gets quieter as clearances tighten up. I'm still hearing some clatter beneath those valve covers.

I haven't crawled beneath the truck yet to see if anything could be loose, such as an exhaust/cat shield.

The truck doesn't shake anything like it did when I had the misfire a couple of months back. I'm thinking that it could possibly be the fuel injectors themselves...I've been present when I had a couple of sets of motorcycle injectors cleaned at a local performance shop, and when they were firing in the test tank I was amazed at just how noisy they were. Anyway, this noise it just enough to trigger my OCD. Anything I might have missed? Alternator bearings? PS pump?

 

Have you checked your idler pulley? Normally it makes more noise than vibrations, but still worth checking. Do you have an automotive stethoscope? If not, I'd recommend picking one up, and just poking around throughout the engine compartment with it to see if you can pinpoint a noise that seems to be related to the vibration you're sensing. I also had a very minor vibration at idle that new coil packs solved. My understanding is that coil packs can wear out and still function adequately, but cause slight vibrations at idle and decreased fuel economy. Just a couple thoughts, hope it helps.

 

Good call on the coil packs, since they are original (2002). Getting a stethoscope this week.

I think the idler pulley was replaced when I had the radiator & water pump done in 2021.

 

New mounts are OEM?

 

Yes. I try and use oem parts in critical areas as much as possible.

 

@Morden - OP did you ever resolve your vibration issue?

 

Still vibing, hasn't gotten worse. I figure it's either the AC compressor or the harmonic balancer.

 

Ok, I'm hunting down what sounds like the exact same thing on my truck. I've done everything you mentioned too. Considering trying new injectors soon. My OCD won't let me stop searching even though it's very faint. Thought I'd check if you'd found the secret sauce lol