I've done a search and I seem to be having the same symptoms as this guy:
http://forums.2gnt.com/dcboard.php?az=show_topic&forum=5&topic_id=49689

I did a keydance and came up with the usual 12, 31, 55, plus the 51. Yeah, it looks like I'm running lean, based on my crappy blinky a/f gauge. I know its not accurate, but normally it goes back and forth at idle, and goes all the way to green, or a lil way towards green when I go WOT. But this morning, as I was idling, waiting for a light, I notice my revs went up a bit, went down, then I noticed idle felt different. As I go, I noticed a lack of power, and some stuttering. I also noticed that my a/f gauge isn't showing any reading.

Going to the PCM writeup on the main site, I see "MAP sensor output / Injector / Fuel pressure / Intake air leaks / Heated oxygen sensor / Adjust S-AFC". So what is the most likely cause for my symptoms out of all these? Bad MAP sensor? Dirty injector? Or bad 02 sensor? What's the best way to eliminate the others? Oh, and how do I test for a bad MAP sensor?

SonicYan aka Mikey
1997 Eclipse RS
Pinoy Reppin' SoCal 2GNT
Best: 16.35 @ 83.05 MPH

Your blinky light gauge measures output from the 02 sensor only. So if the gauge is dead, your O2 sensor is probably the first place to check. Did you cut the wires or splice/solder them? How old is the O2 sensor?

Hmmm, its pretty old. I've never replaced it ever since I owned the car in 2001. So that's prolly it. Haven't been messing around the engine bay area so not sure if its loose or something...altho I had the alternator and ps belt replaced recently. Dunno if it was disconnected in the process.

So I guess the question now then is: Best place to get the O2 sensor? I was searching the forums and I came up with $77 from Bob Kise for the OEM sensor. Is this still accurate? Any other place that has them cheaper? And the OEM ones are just clip and screw on right? No need to solder? Any other O2 sensors that work as well as the OEM ones and are also screw in?

Edit: oh yeah, also found this on the board
http://sparkplugs.com/more_info.asp?AAIA=1205862&pid=1989

Denso 234-4076 (1996-1999) ...1996.5 and up OBD2
Denso 234-4026 (1995) ...up to 1996.5

Hehe, it was actually u Dan that posted it. So have u used this OE identical sensor? Will it work as well as the OEM ones? I read to stay away from the Bosch ones.

SonicYan aka Mikey
1997 Eclipse RS
Pinoy Reppin' SoCal 2GNT
Best: 16.35 @ 83.05 MPH