I'm in a bit of a spot with trying to sort out what's going on with my car. It's a 2003 Ford Focus SE. 3.0L Zetec engine. I got it used for cheap because of its history; two accidents with a rebuilt title.
When I got it, I changed the spark plugs, wires, replaced the valve cover gasket as there was oil in the cylinders, and did an oil change. The instrument cluster was replaced as well. I have since cleaned the mass airflow sensor with the correct cleaner, and ran Seafoam Engine cleaner and Lubricant through the intake, and cleaned the K&N cold air intake filter with the appropriate kit. It ran so incredibly good following that. Later, the thermostat housing was replaced.
From the start the idle was a little rough, though following each of the aforementioned (minus the instrument cluster), it seemed to improve significantly then start getting bad again. And more recently, following the thermostat housing replacement, it got much worse. It vibrates so bad the mirror is shaking.
I checked the oil and noticed at the very tip it looked like a little had been burned onto the stick, but the rest looked clear. Oil still appears to be in good shape. It's full synthetic. The spark plugs are motorcraft double plats. I think I got the base wires for the replacement. It was roughly three years ago.
A friend suggested I look for blue smoke from the exhaust when I first crank up the car in the morning. I didn't see any. There's no antifreeze smell, and the oil doesn't appear to be cloudy at all.
I'm hoping to get an OBD scanner soon, but for now if you can recommend I look at anything, it'd help tremendously with trying to narrow down the problem. I'm hoping it's something I can fix myself.
I should mention I'm on an incredibly tight budget. Please keep that in mind with your suggestions.
Thanks for your help!