I am having a problem with my car that has gotten worse today. I changed my rack and pinion three weeks ago and ever since then the check engine light has been on. The only codes I got was 43 and someting about the EGR valve. Now fast foward to today I am coming home from work and it stumbles and dies while I was second in line at a stop sign. I put it in neutral, and tryed to start it. Well it strated but would hang up at under 500 RPMs and the CRUSE light was on but if I took my foot off the gas it would just die. Well after about 8 tries it finnaly starts so I get it off the road and start checking spark plug wires and any other connections while it is running and everything looked fine so I get back on the road and it dies again but this time it relultently (sp) started. The the rest of the way home it keeps stumbling but when it does I would push the gas alittle more and it would come back to life. When I finaly get home I check the codes and I am getting 43, 43, 51, and 21. I know that 43 is Peak primary circuit current not achieved within maximum dwell time, 51 is Lean air/fuel mixture has been indicated by an abnormally rich correction factor, and 21 is the O2 sensors. Can the O2 sensors or the EGR valve cause this to happen? Thanks.