Got a 1999 Xsara 1,4 Petrol..
Did not run right, so the Owner tweeked the Throttle Cable so that
it always runs at 2000, there you did not feel it missing as much
After reseting the Throttle Cable it has a low Idle but shakes a lot.
After fixing a Vaacuum leak, it got better but still present.
Screwed out the Plugs...all new NGK in there.
Maybe the Ignition Module is bad ?? They seem to be known for Problems....
A low amp Clamp around one cable to the Ignition module.
Would you change the Module ??
I would say its on its way out....