Just bought a 98 Impreza Outback (automatic).. When I bought it the CEL was on and the previous owner said it was because the stock airbox and intake tube had been removed to put a cone filter in its place.. He included the stock airbox and intake tube with the car, so put the intake tube back on.. I was unable to put the airbox back on because the ears on the MAF sensor had been cut off to fit the cone filter onto the maf..
what the car is doing:
Sometimes when I start it, it will idle at about 2000rpm and then drop to 1500rpm, and then when I put it in drive it will drop to 1000rpm and i can drive it with no major issues..
But other times it's different. When i start it it will start at 1500rpm then slowly drop to around 800rpm and start misfiring bad. When this happens it's completely undriveable. But then I can shut it off and start it back up and it will run fine again..
Occasionally, it will be running fine and then start running crappy out of nowhere..
I had the CEL scanned and it read: knock sensor, iac valve, and misfire on all cylinders.. I replaced the knock sensor today and it runs better when it runs good, but it still does the crappy misfire thing sometimes..