Motor witness always on (orange) Focus

This is happening to me several days ago, the light of the orange instrument panel (motor) is always burning either cold or hot. It is a focus 1.6 gasoline of 2001 Motor Zetec se.I its behavior in the start is normal, it starts perfectly, at low revolutions especially below the 1000 gives many pulls but does not get to fold, the idle is somewhat unstable.
Given all this I have changed the spark plug game and the spark plug cable game without any positive results, is any idea about this?
The consumption of gasoline is practically normal and in the escape there are no fumes.
The behavior at low revolutions (below 1000) are too many pulls as if it were in 3 cylinders is my clear appreciation this

Zetec Rocam engine, this engine has many temperature problems and devoted to its structure is complete of aluminum, the theme of warm is quite complicated, I recommend you run a scanner so that you come out of doubt if the light is turned on will be more economical to make the scanner than to try to guess. Now because I tell you about the temperature, look at the exhaust if the sound it makes is poarejo or cut if a cylinder does not check the spark plugs that you took out and see if its color is orange is passing water, if you do not lower your water level it can be a coil problem and nothing else, as that vehicle uses chain and does not strain it is difficult and almost impossible that the distribution runs

Most likely it is the ignition coil, the vehicle can be demanded by the electric failures, it accuses the coil to change the coil

In case it serves you, the same thing happened to me and it was the liquid of the particle filter that is replenished every 60,000 km.
I don't know if Gsolina's engines have this filter.
All the best