Hi , my 07 rabbit has an engine light on and then it sometimes goes off and then it sometime flashes, I smell gas I had plugs replaced as well as the Valvue cover assembly, the car works fine at times and then the light goes. the car sometimes coughs when in third to fourth gear. Im not sure what is going on anymore with this car, many of thousands later and it just keeps happening, I had the diagnostic done and it threw the codes to replace valve cover , we did and it seems worse? Im I missing something? please help