weird idle new o2 sensor and crazy noises

So i searched around and really couldent find a clear cut answer. I have an 89 CRX Si. I replaced the o2 sensor because when i bought my car it was throwing codes 17 and 1 which was the speedo cable which i fixed and the o2 sensor. I went and bought one from my local auto parts store and got a bosch single wire o2 sensor and connector. it was like 30 bucks. took me a ton of effort to get the other one off. had to take off the upper radiator hose and take out one fan to get my big ol breaker bar in there to get the thing to come off. needless to say there were a few things that went on today. So driving around after i leaked out some radiator fluid and put it back together without changing the sensor the car ran fine and was still throwing code 1. when i got back home and changed it out without taking all that stuff off again i put the new one in and it is all messed up. car runs great at highway speeds. when i come to a stop or push in the clutch it goes from 1500 down to 1000 then back up to 1500 the back down over and over. got home and tried playing with it and it started throwing code 1 again. went to taco bell for dinner and i was sitting in line and it was going up and down and up and down so i turned my car off. turned it on and moved up in line and it went up and down up and down. turned it off again. turned it on and no more up and down. same with when i got home was working on it and it would only idle like crap but no occilation. drive it a little and it does it then quits again. i cant ever get it to re occur by doing things the same so im out of ideas. i figured id take the 02 sensor back and try my old one again. see if it goes back to the old way. if it dosent i always have a 1 year replacement on the new o2 sensor i bought might try a new one. anyway any ideas would be great.

Also when im driving around i hear a noise like a mouse scratch or something from the back and its driving me insane figured someone maybe knows what it is.

peep this link... http://www.automotiveforums.com/vbulletin/showthread.php?t=211218&highlight=idle

i check out the page and ill have to try that. also i noticed today while driving it that if it does the occilations if i push in the clutch then put it in neurtal then let out the clutch it quits till i turn off my car again. also i adjusted the idle screw and when i went to change it back from 1500 to 1000 the CEL came on and it was blinking code 1.

The squeeking noice seems like something to do with the rpms of the car. dosent do it much at idle but all of the other time i drive it it does.

Ok so i put in my new o2 sensor plugged my battery back in started her up and no code. drive for about 25 min and it throws code one, my o3 sensor. so i went to take it back and get a new one and i put the old one back it. didnt plug it in. reset my ecu and it does the same thing. light dosent come on or throw a code for about 15 min. is there something else wrong that makes it so that my o2 sensor cant be seen at all? makes no sense that it does the same thing with it unplugged.

make sure that none of the insulation is worn off anyway. The if the bare wire is touching something it could be grounding out. I had to problem for awhile when i put on my aftermarket header.