The car (Renault Megane 1998 1.6e hatchback) lost power (about 500rpm in a bursty rhythm) after I re-ignited on a traffic light, the engine started shaking, and I could smell liquid fuel. There was no obvious place where the fuel could have dripped from. I left the car and checked for any marks on the ground later. About two hours later the car started and ran OK. Then after a few more hours of rest it ran OK again for a few miles, but after a brief stop when I ignited while the engine was hot it started shaking and smelling like fuel again. My first guess would be spark plugs, but I'm afraid of something more serious. What else could be the reason?
UPDATE: Checked the spark plugs -- not them. I have some suspicion about bad fuel as I filled about 5L of petrol the day before.
UPDATE: I tried pulling the the ignition leads from the engine side during the faulty running of the engine. I didn't dare pull them all the way out, but an inch was just about enough to hear the distinctive sound of a spark jumping to the plug. Two of them (1 and 4) failed to produce that sound. I've ordered ignition leads, so I'll soon find out of they were the problem.
I also had another experience I tried driving the car with the engine shaking and about 500 down the road after I stepped on the gas quite hard, it started working properly again.