1994 BMW 325 Random Stalling and dies instantly while still

My car usually drives well. But randomly it stalls w/ light showing real quick. Sometimes, the engine just dies without any stalling or hesitating while I am still driving i.E. 40m/h without speed changes. Most time, I have to wait to start again. It won't start right away. All the electrical functions still work, even if the engine goes off.

Here are some suspect things. My car has soft-top and got wet last winter due to overflows from top-container. So water overflowed into bottom of the car. At the same time, I found the main power cable and the power cable to computer were damaged. So my mechanic fixed popped section of the cables. Since that, the problems started happening. After I dried my car under sunlight w/blow drier, the problems were gone for a while. About 3 weeks ago, I saw check engine light on. The code said 1221, which was oxygen sensor. And this is a key thing: I was stupid. I sprayed carb cleaner through air mass meter. The check engine light was gone. Everything looked fine. Two days later it stalled and died randomly. Somebody said it would damage the sensor. I went to mechanics, and he said examined values of air mass meter was 8; values should be between 8 and 20. I have changed oxygen sensor. Still no light. Working good for 2 days. The problems popped up again.

I remember the symptoms have been very similar since first happening.
So, could you give me some answers, even clues what is going on my car? I really appreciate your time and advice.