I have camry 93, 4 cyl with 145K miles. All on a sudden few days back engine is vibrating or miss firing when it is not running. So when I start or stop on read light or something engine miss fires and car vibrates on and off. I took a guy I know and he adviced we could start with Spark Plug. We changed all spark plugs, but didn't help. He asked me next thing to change plug wires, but this car has all of these changed (spark plugs, wires, dist cap, rotor etc) about 25K miles back. So, I decided not to move any further. When car vibrtaes my RPM gauge also moves.

One clue though, bottom of one of the spark plugs had oil little bit, other 3 didn't.

If I could find out the reason why it is happening, it would be really great. I don't know much about car, and feeling helpless.

please reread post ''engine is vibrating or miss firing when it is not running.''
also oil on spark plug where??on electrode or just on porcelain

please reread post ''engine is vibrating or miss firing when it is not running.''
also oil on spark plug where??on electrode or just on porcelain

Thanks. Well I am not sure what you call that, but oil was on one end of the plug where plug has ankle or L shape.

please reread post ''engine is vibrating or miss firing when it is not running.''
also oil on spark plug where??on electrode or just on porcelain

Where exactly is that post? Could you please paste the link?

Best guess is that one of the replacement plug wires has gone bad prematurely.

I'll second DFBonnets post. It has happened to me. Beyond that, one quick way to isoltae the problem to which cylinder is not firing is to connect a timing light to each plug wire. If you see a steady flashing light on all 4 wires, that eliminates the ECM, coil, ignitor, and plug wire. The only thing left in the system is the connection at the spark plug, and the spark plug itself. If one wire doesn't produce a flash, that is the problem cylinder. You have to go to the previously mentioned components to further isolate it.

Oil on a spark plug indicates worn cylinder rings. That cylinder may indicate low pressure on a compression check. If you are seeing a check engine light you'll have to check for codes.