Multiple misfires 1,2and 3

[Gelbster]

I am as frugal as anyone but ...
To decide on replacing an old sensor - first check the voltage pattern with Durametric or similar. That is more proactive than waiting for a code.
Once you replace the sensors you have eliminated that issue from future problem/code chasing. New sensors may last 10+years of normal driving.
There is the advantage of time saved from "while you are in there and have the tools/time off."
On my 2001 S Bosch sensors are $70 each x 4 .The older 97 .2,5 cars may be cheaper than that and they have only 2. Same reasoning for doing the coils/spark plug tubes also.
Getting a CEL while enjoying a drive is something I'll spend a little to prevent.I agree , it is a hobby not a financially logical issue.Ymev

[maytag]

I decided to put this here, rather than start yet another thread.

I'm chasing a hodgepodge of codes I'm popping since putting the car in for some "upgrades". Most of the upgrades were suspension related, others were maintenance, and still others were purely cosmetic. The few that I think could impact this:

Replaced MAF sensor
New catless Headers & high-flow-cat-midpipes.
Extended the wires on the O2 sensors so they'd work with the new headers / midpipes.

I cleared the codes and took it for a 10-minute drive. Here are the codes it popped for me in that time:


So, focusing on the bank-1 misfires, I took a look at Camshaft deviation numbers, which are both sitting steady in the 1.3 and 2.1 range. So then I went and took a look at the O2 sensor voltages. I think maybe I have a problem there. Watch this short video:

https://photos.app.goo.gl/ZuMjwX6F1XhhYhQM8

You can see that the "After Cat" O2 on Bank 1 is acting quite differently from the other 3. I don't have enough experience in these parts to know which is correct and expected behavior, but I'm seeing 3 acting similarly and one outlier. We do have an O2 sensor code (P0130) but that's for "Before Cat" on the same side. I'm not sure what to make of all of this.
I did have to extend the wires on my O2 sensors to work with the new headers & midpipes I installed, And it's also possible one was bad to begin with.

Now the other thing I'm thinking: the misfiring cylinders (1, 2 & 3) are on the same side as the coolant pipe that I had spring a leak. I guess it's theoretically possible I've saturated the coils? possible... but how likely? I have some spare coils & plugs I could swap, but I'd rather not chase squirrels here.

Does anyone know what I should expect to see for O2 sensor voltages or resistance?

Any other place y'all would look?