Idle fluctuating, and 02 readings off

[Qosmo]

Car is 99 civic dx with b16a2. Had the same idle issues with b18, but was remedied by decreasing the IACV duty.
After b16 swap same idle issue with no fix.

Recently installed AEM uego 4410, using d10. Since the idle fluctuates its hard to get a reading off the wideband but it looks like its between 13-14.

mostly trying to figure out the idle issue, so I have added a datalog

data1.s3d

[Spunkster]

You appear to have an air leak somewhere which is causing the fluctuation. Is this an OBD1 or OBD2 throttle body?

[Qosmo]

OBD2B throttle body. I've disconnected the Evap solenoid valve, and blocked off the top port. I've also blocked off the cruise control port.
I've got new gaskets all around, new cap rotor, wires and dizzy internals. The IM gasket is yonaka and not oem.

I can't properly set the timing as the idle surges up and down very shortly after starting the car. Sometimes it will idle longer, but it's always around 2k rpm. Then continues surging from 800-1800 and it seems like the car is going to stall. When I give it throttle it sounds like misfiring on decel, kinda popping a bit.

The head has also been machined, new head gasket, new valve guides, skunk2 valve stem seals.

The IM gasket is yonaka and not oem. Last thing I might try is a OEM gasket for the intake manifold.

I can upload a couple more data logs of idling. Thanks

Datalog-211013-000.s3d

Datalog-211013-001.s3d

[TTR]

Start the car and spray the intake manifold and throttle body down with brake clean. If the idle changes there is a leak. If the motor is hitting over run cut its getting too much air. Make sure the throttle plate is fully closed, air bleed is set or shut for testing. Pull the intake pipe and plug the hole that feeds the IAC. If it doesn't die when you plug that hole there is a leak somewhere.

[Qosmo]

I've tried plugging that hole while the car is warm and cold and the car does not die. The iacv is new, so I'm guessing there's still a leak around the intake manifold gasket.

I'll try and oem one today and see if it helps.

[Qosmo]

OEM intake gasket did not solve the issue

[Spunkster]

Check the throttle body gasket.