My 1994 Opel vectra 1.6i has a problem. When the engine is cold, it works properly. But after a while the water heats up to 100, the speed suddenly slows down and the car runs on a lower gear. The car works both with gas and petrol. I thought it might be the injector but does the gas have anything to do with injector (petrol has for sure). I've even changed all my spark plugs, but again it's not working. So, if oyu have any idea what could be xcausing it, can u please reply as soon as posssible?
Thanks in advance,