I picked up a 2002 Mazda Protege with 150k today. The car runs and drives fine but has a rough idle, feels like a misfire and a code p0300 comes up (random misfire). It acts rough only at idle but does fine under load. I replaced the plug, wires and ignition coils but the problem remained. I cleaned the maf and the throttle body (had it removed and cleaned good) and now the car starts but dies right away. If I give it a little gas it will stay on and it will drive fine but as soon as I stop it dies. I used the maf cleaner but I feel like I killed it. I also read on some mazda forums that egr valve causes a rough idle. I am just trying to gather some ideas. Please feel free to shoot me yours. Gas is $5 and I am trying to get this thing running on a budget. I cant get tags as I cant get it through a smog test with a check engine light on. Really hoping to get it fixed this weekend. Any help is appreciated.