The Nissan Path

I had a cylinder misfire on cylinder 5 so I changed the plug yesterday.

Before I had changed the plug, the pathfinder was shaking uncontrollably and very noticeable. The check engine light was on and then started blinking so luckily I was close to home and did not drive long.

After I changed the cylinder 5 spark plug everything seemed great. No shaking when in idle, I took it around the block and had no issues. Driving to work today something gave way 10 minutes in and it started mildly shaking and had very little power to get off the line quickly. Check engine light came back with cylinder 5 misfire..
what do I check next ?

What was the condition of the old plug?

Coil pack next maybe.

The old plug was bad. The center electrode was almost gone. I waited too long.
But even after putting in the new plug it came back.

I will google on how to test the coil pack. I did not have starting issues so I figured that the coil pack wouldn't be the issue, but im probably wrong.

I just took it around the block and it feels like its not getting gas. Kind of like when you run out of gas and the engine sputters.. does that make sense and/or help ?

When you get a single cylinder misfire, it's more likely to be a bad coil pack than a bad spark plug. Since there are individual coil packs (one per cylinder), one bad coil pack won't cause a startability issue any more than one bad spark plug. FYI, I purchased Hitachi coil packs (made in Japan) for $35/each not long ago from Rockauto.com. Hitachi makes some of the OE coil packs for Nissan, among other things. You could swap the #5 coil with another and see if the misfire code jumps to the other cylinder, which would tell you that the coil pack is bad.

I swapped the coil pack from cylinder 5 and cylinder 3.

I had the guys clear the codes and Codes came back. Not only did “cylinder 5 misfire “ come back, now “random cylinder misfire†as well !!

Wouldn’t that mean that the coil pack is fine? If so, what do I do now !

What other codes are present?
Mileage you have stock exhaust stock cats it might be clogged

I did just pull a 420 and 430 catalytic code. I knew that was an issue but would that be the cause of the car shaking and not getting enough hp to get up and go?

I got new plugs so I am going to swap out all 6 this weekend to check first.
Should I get a new coil pack and try that too?

I have 180k miles on stock cats. I am replacing the exhaust back, now that I just pulled these two new codes I am sure the cats are gone and need replacing too.
Should I replace the spark plugs and exhaust first, then go from there? Or what would a good checklist be to do first, second,

Changing plugs made my 0430 go away. But the code was the only indication I had (along with a single worn plug, on the side where I had a VVT issue...). That's usually step one, then go for the expensive things like cats and O2 sensors.

By swapping the coil pack of the incident cylinder with another and have the same misfire code re-trigger, it tells you that the coil pack was not the problem and the misfire is due to something else at cylinder #5. That could be a spark plug, bad fuel injector, circuit issue with either the harness to the coil pack OR the fuel injector, faulty ECM or a mechanical issue with the engine.
Since you replaced the spark plug and it started running well for awhile and then acted up, again, it would likely not be a mechanical issue. It's possible it could be an intermittently failing fuel injector or a harness issue, but you'll have to do some tests. If you want a well laid out diagnostic procedure, you can follow the diagnostics for the P0305 code in the "EC" (Engine Control) section of the factory service manual for your vehicle. You can access a free, online FSM at NICO Club's website.