Hello, since February I have a 88 Saab 9000 Turbo, where everything runs smoothly, except just “CHECK ENGINE”. In idle the good piece is jerking and the speed falls partly white very briefly up to 200 UPM and then again up to 1000 and sometimes, when it catches again it turns without gas up to 1500 UPM. However, as soon as I give gas and drive it usually runs completely round, except that it sometimes jerks a little bit and loses its performance for a short time. My guess is the petrol filter, especially since the petrol pump is extremely loud in idle. I hope here can be helped… Greeting from Plauen Micha