Another possibility if you have an older Clio 1.2, is the low tension wires which run up to the single "black box"
pack on the left hand side of the engine on these models.
Follow the wiring back from the
pack plug, down past the brake fluid reservoir and check to see if the wires have been rubbing on the metal brake pipes. This can cause the wiring insulation to be worn away and an intermittent short circuit can occur. This fault can give the same symptoms as a failing
(I changed a
pack before the real problem was found! We were quite lucky there wasn't a fire I reckon).
We also had an intermittent vague burning smell which we couldn't trace for a couple of weeks before the car finally stopped running, and the battery hada tendency to go flat if the car wasn't driven for a few days....
If this has happened, replace or use decent insulating tape round the rogue wire and re-route the wiring so it doesn't happen again.