I found out why i keept getting codes 41 and 91...well It made my car run in limp mode, cause it told the comp I was running dangersouly lean, I even bought ne O2 sensors, still same problem,Ive check vaccum leaks for weeks. still no fix , I had this problem and have been chasing it for 4 months...and it was all because of the Hego ground wire wasnt hooked up....and I found it, even though I have looked 10 times for that wire I finally found it...and now my car runs freakin perfect, now I can smog it, then rip all the smog shat off there...