Slight misfire only after warmed up
 

I just bought an S13 with a 97/98 dual cam swap and 5-speed (auto ECU), with a bunch of vacuum leaks and no alternator belt (:picardfp:). It has been slightly misfiring, mostly after warming up.

I threw a belt on the alternator which massively helped of course. I also put in new spark plugs last night.

I capped all of the obvious vacuum leaks, and I sprayed Windex everywhere tonight while it was running and it didn't seem to idle rough at any point from a vacuum leak, and there was no arcing around the spark plug wires.

At this point in my "troubleshooting" would it probably be a bad fuel injector? It seems to be a really slight misfire, that is most prominent at idle after warming up. I'm going to clean the MAF in the morning, and I'll pull the O2 sensors and check them as well.

Any thoughts? Here's a video of startup and an exterior idle clip. In the first video, immediately after cranking you can hear it slightly misfire between 1500-2000 RPM but then seems to idle smooth:

https://www.youtube.com/watch?v=DVoclvb9oAk

https://www.youtube.com/watch?v=UTdrrVyZ-E4

ordered new injectors..hoping that's it

Doesn't sound bad to me.

Maybe my ears have gone to $#!t though.