I own a 1995 Ford Crown Victoria. It got 98000 miles on it, with a tune-up in the last year or so.
For the past 8 months, the smell from the underside of the car smelled like rotten eggs. Or, rather, old egg salad. My feeling was that the catalytic converter(s) were going bad and needed to be replaced. I'm not sure this was the cause but I remembered others talking about similar situations.
Last week, when backing out of my driveway, my car lurched a little bit. I don't know why it happened, but since then the car has not run right at all. Later that day the check engine light came on. I had the codes read, and it was P0303. Cylinder 3 was misfiring.
I checked all of the wires from the split distributorless arrangement. All wires sparked. I pulled the sparkplug from cylinder 3 and it appeared to look OK. It had a little carbon buildup on it but nothing I haven't seen before in good sparking plugs. When I turned on the car and pulled the wires off one at a time, the car's idle dipped slightly, so I am confident that all plugs are firing normally. I am going to replace them just to make sure, but I don't think the wires or the plugs are bad.
I replaced the fuel filter but that did not help. I also checked the PCV value and there is vacuum, so that appears to be working correctly.
Since this incident, the rotten egg smell has gone away, and has been replaced by a burning smell.
I have no loss in real power of the car. I can still accelerate rather well, and shifting gears is smooth. The only difference I hear and feel is when taking off and when idling.
Any ideas?