Hey y'all, new to the forum. I've been having a frustrating issue with my '98 SE lately, which really came out of nowhere and so suddenly. I was driving on the highway one day (70 mph cruising if it matters) and noticed it started to stutter slightly every once in a while, something I've never noticed before. A couple days later on that same highway, it went from a slight stutter to very apparent misfiring very quickly. The max rpm I could get the engine to progressively shrank as time went on, eventually getting to the point where it wouldn't even start.

After doing what I could in a remote area, I noticed there wasn't a spark when I did the old screwdriver-stuck-in-spark-plug-wire trick. Naturally, I replaced the distributor cap/rotor and an ignition coil (they were cheap). After replacing the ignition coil, it seemed to have fixed the issue, running and revving like normal while parked. However, when I tried driving it around, the same thing started happening within minutes, and I barely was able to limp it back home. While diagnosing fuel pressure, I noticed that the engine will sometimes 'snap out of it' and idle perfectly smooth at 1k rpm, and when I rev, it goes wild again.

I don't think it's a fuel issue because 1: the missing spark I mentioned earlier, 2: a new ignition coil seemed to help, 3: using a fuel pressure tester reveals the pump is giving a steady 35-40 psi. I've only been able to take out the right bank of spark plugs (the ones not covered by the intake manifold), and they look due for replacement, with very apparent wear patterns. But with what I mentioned about the periodic smooth running, it makes me think there is a sensor issue somewhere. There hasn't been any check engine light to indicate a faulty sensor though.

TLDR: Engine doesn't run smooth, rpm maxes out way too low. New ignition coil temporarily fixed it, but quickly reverted back to rough running. No check engine light, and steady fuel pressure, my instincts tell me it's an issue somewhere in the ignition circuit.

I tried recording what is happening. Sorry for the shorts format, youtube formatted it like that.
https://youtube.com/shorts/OvFNfK1ecIw

This one is where I discovered where it sometimes will run smooth at 1k rpm, you can hear my confused "what?"
https://youtu.be/pndj0Tl-8nA

As I usually am when I come to forums for help, I have no idea what to do next.

Update: After installing new spark plug wires and all but the 6th cylinder spark plug (I don't currently have the means to get to it right now), it now runs well, for now...
I don't completely trust it yet, as I thought I had fixed it before, but I was proven wrong quickly in that instance.

I have a theory as to what happened though. When I first took apart the distributor, I noticed there was a significant amount of dust and metal shavings in there, which seemed to come from an exploded bearing. The rotor spins just fine, but I guess that bearing just dried out and some of the balls got shredded . What I think part of my issue was is that dust was getting in between the metal disc and ignition control module (ICM), which as far as I'm aware uses light to indicate when to throw spark, causing faulty signals. Before I put everything back together, I blew some compressed air in that gap of the ICM. Now I can't say for certain whether cleaning the ICM or new spark plugs helped more, I can say sure it was ignition and not a fuel issue.

I plan to try and replace that bearing some time down the road when I have the means to do so, as well as obviously get that last spark plug replaced.

Someone from another forum was saying this is apparently a relatively common issue in 90's Nissans that use the same distributor. The top bearing gets worn out and not only gets debris everywhere, but also allows the rotor shaft to wobble, which isn't good.

This link has some instructions on how to replace that bearing instead of buying a whole new distributor.
https://www.clubfrontier.org/threads/di ... ra.350719/