Hello together, first time the vehicle data: Manufacturer: KIA MOTOR (ROK)Model No.: RIO Kombi (DC) (RS) ccm: 1493 Type: 1.5 16V Year of manufacture: 08/00 – 02/05 KW / PS: 72 / 98 Key No. : 8253 / 329 When I start the car, everything is fine. After a short warm-up phase the engine purrs like a kitten. Also mentioned, behind is a sports exhaust with a really good sound. Otherwise the Kia is completely unobstructed. Now to the problem, in the first gear it pulls normal. the second one is really sluggish up to a certain point ( 30 – 33 kmh ), then there is a thrust as if a turbo is in use. the whole goes on in the third and fourth gear. The fifth gear is then again problem-free up to the next Macke. Then comes a slope in the course of the road the engine starts to bubbling and I can then give gas as I want, there is nothing more. then I have to see that I come to the right and turn off the car. After a short waiting time can This game is unfortunately repeated very often lately. It’s not quite as funny on the highway (strips) when the children are sitting in the car. Finally I changed: air hose (was torn) spark plugs (that wasn’t it) valve cover seal coolant thermostat Maybe someone from you has some advice, or unfortunately someone already had such a problem?I thank you already for your answers!!! [b]MfG