otm. 307 strange complaints

Hello friends, I'm new to you. I have 2005 automatic 307 Xt vehicle and 65,000 km. I have been driving for about 3 months. I have no complaints when using it in the city. However, when I start to do some speeding, after 70 km, the vehicle has a repeating dilemma, which is every 2-3 seconds. I do not know how accurate the term I use, but to describe it, it is as if there is a hand on the rear bumper of the car and this hand pushes and releases the vehicle slightly in 2-3 seconds. This startle or shake occurs in about half a second and repeats continuously, up to the limits of 100-110 km or increasing my load on the gas. I don't feel when I increase the gas. When I take my foot out of the gas, the movement starts again if I let the vehicle slow down by itself or keep the speed constant by reducing the gas. I understand this best from my own belly. My belly car goes at an instant forward and back in 2-3 seconds while the vehicle is driving at a constant speed . Authorized service Diamond auto said the ears of the engine before we changed but the story. Then the disc-pad was prevented, the disc lathes and pads changed the story again. The last axles were said, but it was not convincing to me. So I called the service a HOP and took it to the private. Your gearbox oil pressure is 10% lower solenoids, bushings etc. They said something like, and they made a price between 600-800. I expect help from friends who have experience in this matter. Respects

My friend, the problem is an electronic malfunction, I don't think it's a mechanical thing. The same was with my 318 BMW, nothing up to 90, doing between 90 and 120, not after 120. I got on with it. The problem is electricity - electronics.

Electronic parts checked but no problems found