Just recently when starting my car from a cold nights rest, it jumps alittle on the inital start, idles right out within 2 seconds so its not a huge issue but possibly a sign on a woren part or sensor dieing, So heres the sccop, when i get in it in the morning i turn her over normally 3 cranks on one she goes to 1000 rpm's and holds steady, though the last few monring its jump to 100 as normally and for less then a second flew down like it died but then goes right back up to 1000 its stumbling big time, i have in the last few months replaced : Transmission, o2 sensor, cleaned throttle body, full tune up ( this woudnt hurt to do again but the car runs well all other times ), Replaced all and i mean every vac hose, replaced flame trap and hoses connected to it, replaced main air intake hose to throttle body, All new belts ( except timeing ) I have inspected wireing harness and its in supurb condition, Tested alternator and is working perfectly. The check engine light is not comming on but i am pulling the following 2 codes from the ODB

2-3-1* Fuel trim (lambda control) too lean or too rich at part load }If too lean: air leaks, low fuel pressure, bad sensor }Engine stops when starting from cold; high fuel use or,2-3-2* Fuel trim (lambda control) too lean or too rich at idle }If too rich: high fuel press., leaking injector } various driving problems
1-4-3* Knock sensor signal absent or faulty Faulty wiring to/from/in the knock sensor Poor acceleration,

I just last week replaced the 02 so i know it isnt that,is it possible the Knock Sensor is causing me this problem? any clues ideas or thoughts at this point would be appricated as i keep my car running so well most dont understand why i put so much money into it.