ok so the engine has been choking and stalling for about a month now. I had thought it was the knock sensor, then everyone said it cant be. Yesterday, i barely made it home because the xterra turned off on me on my street (thank god) and wouldnt turn back on, it would crank, sometimes it would turn on, but just for a second. then it didnt turn on at all. I also noticed white smoke coming out of the intake hose/air filter. This morning i tried turning it on, it started up, but im too scared to drive it anywhere. I checked my fuel sending unit's corrosion, and its as clean as a whistle.

white smoke coming from the intake?

sounds like you aren't getting spark, and the engine is flooding because it isn't burning off the gas

Check your distributor.

it turned on today, and the RPM kept going up and down until it shut off by itself

I am having the same problem with my wife's. It started out little, just a little stumble and the RPMs would jump around. It got progressively worse, anytime we press the gas it would stumble and try to die. now it will rarely start. I was thinking it was a fuel pump. but i'm not a mechanic? could this be a spark plug/wire problem? I replaced the fuel filter and filled it up with quality gas with heet additive.

We are desperate, the day after her car broke down, i totalled mine. thankfully it wasn't my fault and we have a rental. But I need help fast! Thanks.

take the cap-rotor- and electronics out of the top of the distributor so you can see in the very bottom is there any black dust?

I took off the rotor and I can't get anything else out. But with a flashlight I can see down to the bottom of the distributor. I can see ball bearings, and also, there are a lot of metal shavings down there. I am hoping that is a sign that this could be the solution to my problem.

its dead time for a new one. make sure you get the casting # off the old one, there is at least 5 different dist and they are not interchangeable.ebay has the best price if you can wait.

Thank you for your insight. I will buy one and install it. is this something I can do myself? I am pretty mechanically inclined. I have never ran into this though...

piece of cake .you will need a timing light . bump the engine around till the rotor point to #1 cl take the hold down bolt out ,unplug the harness pull the dis ,put the new one back in ,be easy on the hold down bolt it strips just looking at it plug the wires back in , set the timing.please take the old dis down and take some fotos of the loose parts in the bottom for other x friends to see and post .

Certainly. Thank you. I will post the photos when i am finished! Thanks again.

transmission maybe?