97 nissan stall at adle

hi! i realy need some help, i have a 97 nissan maxima, like 6 month ago start hiving mi the knock sensor code but no sintoms so i didn`t replase it then have the camshaft sensor put a new une but still haven the same code but now it stall at idle it just stumble then stall it restart and i can fill a bad smell from exhaust like runing rich i here that is a sintom of air flow meter going bad can anybody tell mi how to test it i know it has othes codes but i been told those sensors don't couse the car stall please help mi by the way i did chech fuel presure and it is 35 psi at adle