I've had to do a lot of work to my 1998 Pathfinder since I got it about two years ago-- lots of replacements. Also, bear with me because I don't know much about the mechanics of my car,
The distributor and fuel injector was just replaced a month ago, but it wasn't quite running the same. It feels like there's slightly less power than before.
It's been making a weird sort of metallic growling sound when I'm in neutral. This happens if I'm just sitting and idling, or if I throw it into neutral as I'm coming to a stop. The sound will go away when I push the clutch in, or sometimes fade on it's own. However, I took a trip at highway speeds on Saturday and it was about 250 miles. When I went out on Sunday, I filled up and noticed that it was making that loud metallic growl while I was in first gear with the clutch in. This is the only time I've ever heard it make the noise while I was in gear. Engine also revs itself a few times on cold starts.
My father initially thought it was the throwout bearing but I'm not entirely sure now, since the sound usually goes away when the clutch goes in.