hi.
I`ve noticed that very often my marea is loosing power. It hapens very random. Sometimes its like that for few days than its ok for 1. sometimes it runs ok and when reducing gear and starting accelerating it loosing power again. Engine on idle is shaking all the time and lights are hmm i can see they loosing power too when on idle. I have chagned sparkplugs(ngk) putted air filter from K&N, went check it out in garage and been told coils are ok. Checked battery today. Started engine waited 5 mins till revs calm down. After 5 mins revs 750 engine shaking like always: 14V, Engine shut down: 13V. Battery is WARTA 250A 50ah. Also before last coil three cables are unprotected for about 1" lenght i can see cables.

Marea 1.8 16V elx 2000y

----------------------------------------------------------------------------------------
Just isolated thoes cables with tape and no diferrence.

I've had a problem with low/unstable idle speed, also loose of eletrical power at idle.
The charging voltage at idle was only about 12V, so i replaced the voltage regulator on my alternator and problem was solved.

Yea need to take a look at alternator. Is there posible to take readings from alternator on switched on engine?

Just measure the charging voltage on the battery with the engine running.
You should measure around 14,5V.
See enclosed guide.