Sputtering at times

2000 Ls V6, 145,000 miles, Ok the other morning I start up, and sitting waitng for it to idle down, when it does it starts to sputter like its gonna die, so I hit the gas kinda rev it up a bit, and it's fine, it drives fine with no problems, however I was sitting in it today and reved it up at around 3,000 rpms it starts to sputter, but I punched it on the way home and no problems, put it back in park and reved it up and it did it again around 3,000 rpms, any clue what's going on here?

There's a good chance the issue is due to a vacuum leak, and quite possibly the PCV elbow under the intake manifold. Not a real fun project, but doable if you have the time, tools, and desire. It could also be a slow Idle Air Control (IAC) servo or possibly even a weak battery or loose/dirty battery connection(s).

-Rod

2000 Ls V6, 145,000 miles, Ok the other morning I start up, and sitting waitng for it to idle down, when it does it starts to sputter like its gonna die, so I hit the gas kinda rev it up a bit, and it's fine, it drives fine with no problems, however I was sitting in it today and reved it up at around 3,000 rpms it starts to sputter, but I punched it on the way home and no problems, put it back in park and reved it up and it did it again around 3,000 rpms, any clue what's going on here?

As far the problem at 3K RPM in park or neutral goes... This is correct normal operation. The PCM will cut fuel when the engine starts to go over 3K RPM when in park or neutral. This [cutting the fuel] causes it to run rough.

Ahhh, good call. When I read the original post I interpreted that the car was revving up to 3k on it's own. Now that I re-read, I think you're correct, the driver is revving the engine and noticing the rev limiter.

-Rod