Help with 3.4l Rough Idle Diag

[YotaFun]

Looking for a fresh idea gents.

My Step fathers 2002 Toyota 4Runner Auto 3.4l V6 with 316k miles on it has had a rough idle for some time and a code for knock sensors.
Today I went ahead and did the knock sensors, the wire for the sensors, new gaskets for the upper and lower intake, new valve cover gaskets (they were leaking, and for 316k it looks good underneath), and a new throttle body (suspected to be bad due to pink milk shake long ago, could never get cold start idle right).
Timing belt done 50k ago and looks good still, Also did a seafoam treatment through the intake tonight. Took it out for a test drive and it seems to have improved.

Parked it in the drive way and thought "Swing! It's Good" and then a second after saying that the idle starts to stumble a bit again...

No pending codes, runs great while going down the road. No smoke of any kind, No fluids mixing anywhere, sprayed down to check for vacuum leak, all good. I'm stumped.

I know I will here plenty say its just time to let it go, and honestly I do agree even though this is the truck that started this addiction lol. I am just curious. I want to say I got it right before it finds permanent resident in a Junkyard.

Just looking for some fresh Ideas...

[4x4mike]

Injector?

Does the idle stumble then correct itself? You said you replaced the throttle body but hows the IAC valve look?

[YotaFun]

I ran out of time. The work I did was a vast improvement. A fellow tech who is more familiar with transmissions doesn't feel the problem is trans based. He feels it may be a weak valve spring issue.

I was unable to get a new hose to do a compression test in time. The 4Runner performs great. It helped if you shifted the trans to neutral at stops. Even when the idle would lug at stops in drive it was in normal parameters per the FSM.

Only other possible item I can think of are failing injectors. But without the ECU catch the miss and not having a oscilloscope or voltmeter to check I can't confirm.

I gave him a heads up, while I'd does feel better to prepare and drive it till it blows, I have a feeling the transmission will go first. And with the frame starting to rot it's time.