3RZ 2.7 engine vibration/shudder

Hey guys, you may have been reading my taco lean/lift thread i started last friday. Now that I'm waiting on the parts to arrive, I'm scratching my head on another minor issue ya'll might can chime in on.

Truck is at 77K miles right now. I noticed diminishing fuel mileage and power, so I did a full tune up over the last couple weekends. This included:
Starter contact rebuild
R&R fuel filter
R&R Spark plugs (3x, once with Denso oem's gapped at .32 and .43, then NGK oem's at .43)
R&R Plug wires with NGK oem
R&R air filter
Clean MAF
Seafoam (first attempt failed, second worked)
Oil & filter

My question is, since around the first seafoam attempt/first spark plug change, It seems the trucks shakes more at idle than i recall. It also seems to have a "shudder", as in every few seconds the vibration feels slightly harder. It doesn't vibrate excessively, it doesn't seem to be misfiring, non-idle operation is fine, and there are no codes thrown.

I've checked around for vacuum leaks and found none. But what I'm thinking at the moment is, could a fouled IAC cause this issue?

My first attempt at seafoam (never done it with this truck before) I tried using an old can of spray-seafoam directly infront of the throttle plate, which didn't really spray well. Then tried the traditional can through a small vaccum line off the front of the valve cover which fed to the TB, but didnt provide much vacuum. When done, the truck never smoked/cleaned like usual on restart.

I later did a seafoam treatment through the brake booster line, restarted after sitting, and it did what it was supposed to. Hella smoke and a stronger feeling engine.

My thoughts are, could i have puddled some seafoam in the IAC on the bottom of the TB and dissolved/moved some deposits which are affecting the IAC? it does seem to not like returning to idle after a quick bump on the throttle.

If not likely, any other thoughts? I know these engines aren't lexus smooth, but i never noticed a shake/shudder until i did the first round of tune up, which included the failed seafoam attempt and new .32 denso plugs/old wires (one of which i thought i damaged, hence the new NGK wires and NGK plugs)

 

How did the throttle body look? The butterfly appear to close all the way? What RPM does the engine idle at? Have you tried pulling the underhood EFI fuse or disconnecting the battery so the ECM has to remap the fuel trim values?

 

I haven't checked the TB very closely, so I can't say on the looks or the butterfly. RPM's are about normal, 650-750. When I did the plug changes as well as starter, the battery was disconnected so it has reset the ECM mulitple times.

 

Gotcha. Might be worth cleaning the throttle body and valve. If something else comes to mind, I'll post up.

 

That's next on my list, along with a more in depth check of the vacuum lines. Probably will clean the PCV as well.