Hello, I have an '85 Maxima, 156k miles. The past month or so it's been idling rough. Also the flywheel for the the starter is starting to "grind" sometimes too which isn't good either but I don't know if it's related to the Big Problem. (I just had it replaced 5 years ago)
So, a month ago, when first driving, the RPM drops to 600 (from 700 normal idle) and idles very rough during the first 10-15 minutes, like it's going to die (but it doesn't). Meanwhile, I'm white-knuckling it til it warms up more and stops being rough. Begging it not to die isn't going to work one of these days...
I brought it in a couple weeks ago and my mechanic did a full tune up and adjusted up the idle. It's now better in traffic but since then, when the car is first warming up, the engine begins to loudly "sputter" or kick dis-rhythmically and the RPMs fluctuate up and down, mostly down. It feels like it's going to die but doesn't. It then evens-out and stops sputtering after a few minutes. I called my mechanic and he told me to NOT give it any gas while warming up (it still sputters, though), and to try another brand of gas (was using Unocal76 so I filled up with Shell premium last time).
Tonight, what freaked me out was that while driving the 2nd block I heard a metal-on-metal grinding noise even when I stopped accelerating and went to pull over. The flywheel grinded when I started up so maybe something got knicked off the flywheel and got in the engine? The noise stopped after about 5 seconds and I continued on, with my stomach in my throat - as it then idled rough and the RPMs jumped up and down at the first 4 lights. sigh.
Sorry this is so long but I'm worried. Getting another car is out of the question and so is spending more "exploratory" money. My mechanic is a good guy but seems stumped. Maybe it's the O2 sensor he says, or it could be running lean(?) or ?? Also, when I got a new battery in December, Sears told me my 6 year old alternator was going bad but my mechanic disagrees and says they always tell people that. I'm not sure he's tested it though.
Any help appreciated. Thank you.