Good Afternoon Friends!
I have a problem, help me beg doctors in cars!

I have a scenic 1.6 16v 2001/2001 with 76.000km, I bought it about 8 months she was with 69.000km. Out of nowhere started to show a defect that cruel to call in the morning she takes everything as normal by the book to go with it until everything normal but if i stop the car for example to go to the super market for about 5,10,15 or 30 minutes what happens is that when starting it takes is normal acceleration, but after about 50 meters or about 20 seconds gives a hole in the acceleration as it is over or if the fuel shut off the car, so the accelerator to the floor order very quickly and return to normal and the car is good until you stop doing this process again and again. It happens from 10 to 5 to 6 that, but for example if it was some 50 days without showing the defect. I'm going crazy, I took advantage and sent for review in an automotive center of a great friend of mine, dear, and was replaced fuel filter, cleaning the injection, I took the belt was already well round then swapped the whole kit, candles and pass full system the car and had nothing to fault injection.
The cruel is that it does not illuminate the light injection in any of these panic! Worse, when it starts to fail if not accelerate and let's see what happens he does not die, just get the idle below 500rpm, if he's choking hold accelerating for about 8 seconds back, but as I said, accelerate to the bottom and get your foot it back faster. Friends help me, because in a forum Renalt speak only shows that this defect in 2001 and over the scenic 1.6 16v engine and this year that has equipped the clio!
But have not found anyone who solved or resolved not posted!
And when the mechanic stuck the raster and walked to the car he gave the defect, but not accused in the raster, cruel. The mechanic tested all the sensors according to him!

I anxious for help, and understand a bit of mechanics!