It's a 2005 G35 Sedan with the sport package. The clutch pedal has issues returning after being depressed. It just started acting like I wasn't pressing the clutch at all. If I bleed the clutch, it goes away temporarily, but comes back in about a week. It has a newer clutch and I just replaced the slave cylinder and lower clutch line. I'm out of ideas. It seems like air is getting introduced into the line, but I don't know. Anyone have an idea?

I think I have this issue as well. Sometimes the clutch will be very easy to press in until it's disengaged. What I do is pump/wiggle the clutch a bit at a stoplight and soon it becomes stiffer again.

It may be the clutch master cylinder. I'd check that first.