Engine stuttering and dying



I have 94 Eldorado. The problem happened a few times so far. It may be a coincidence but just after making quite long left u-turn the engine started to stutter and finally died. After waiting a few minutes it was able to start and died again. After one more try it started again and there was no problem for a week. Next week it was again loosing power for a half a minute but did not die. I took it to the shop, they did not find anything, I decided to flush engine since it was really dirty. And it was ok for a week. Yesterday just after refuelling (again coincidence?) engine stuttered (this time very badly), was loosing power and died several times in a row. When I started it the hand of RMP gauge was moving uop to 2K by itself. Engine was accelerating and decelerating by itself. I did wait again a few minutes, I did try to start several times without a success. After a few times it finally started, stuttered a little bit more and for the rest of drive (about two miles no problem). However i expect it can repeat again. What is wrong?