Well, the DAMN! check engine light came on again for the 6th month in a row, boy i just want to kick my car now everytime i fix something within a few weeks something eles dies, hell and sadder it all started with the transmission going out, anyways, i pulled the codes after getting to work this morning and got 143 ( Knock Sensor ) 231 ( Lambda Sensor ) 121 ( Air Mass ), so i am comming to you guys first for symptoms of what i should be replacing first as the two work together when one dies the other goes off as well till you fix the one that's out, need some help here, was cruising at 80mph when it kicked off noticed immediately a huge drop in power accross the board at any speed, car still starts amnd idles but of course its alittle off, i decided to pull the plug from the air mass idle flew up, put it back on no change , someone said i should be checking the lambda sensor for voltage, but i dont know how to use one of those testers even though i actually have one, nor do i know how to hook the thing up to it ( its a 3 wire on the 89 ). Any help or suggestions would be greatly appricated as i just want my car back.