engine lights on, car tends to stop, elect?

It happens sometimes and last for a few days,: I hear a "click" (electric sound) the engine lights turns on for a few seconds, and the car loses speed, it feels like it is going to shut down the engine and stop.... and then it pass and keeps going...my mechanic could not find anything....

Is it a single click o a continuos ticking?

It's a single soft clikc, engine light turns on, revolutions go suddenly down, last a few seconds and then keeps going normally,

Hhhhmmm.... hard to diagnose without knowing exactly where it's coming fom. Is it coming from under the hood or in the cabin? Left or right side?

Does if feel as if your fans are kicking on? This might be it.

go to a autozone see if they will beable to pull a code.