i have a 97 cavalier Z24. When i first turn it on, it studders and the RPMs go up and down when its not moving . It's not running correctly and sometime the check engine light comes on . So i took it to Autozone to have it hooked up on those machines they have . At first he said it was the crankshaft censor so i replaced it . It didnt work so i took it back and they told me it was 1) Map/Baro circ. high input which i heard would cause 2)random multiple misfire of the sparkplugs i guess?? i'm not sure . And they said something about the Camshaft censor. I'm curious if this is a common problem and could be fixed without taking it to the garage. Should i replace the sparkplugs or the censors ?

I also had my check engine light on ans az said it was a multiple cylinder misfire. They said all i needed to do is get the wiring to the spark plugs replaced.