Volvo 940 engine missing at idle and sluggish performance after tune-up and transmission service on Volvo 940

Some Volvo 940 owners report experiencing engine missing at idle and sluggish performance following a tune-up and transmission service. These issues may stem from problems with the ignition system, such as faulty spark plugs or ignition coils, which can lead to engine misfires. Additionally, owners have noted that fuel system problems, like clogged fuel injectors or a failing fuel pump, can contribute to poor engine performance. Malfunctioning engine sensors, including the mass airflow or oxygen sensors, may also affect performance, necessitating testing for accurate data transmission to the engine control unit. Furthermore, vacuum leaks in the intake system can disrupt the air-fuel mixture, causing rough idling. Some owners have found that issues related to transmission service, including incorrect fluid levels or types, can exacerbate sluggish performance. If these problems persist, it is advisable for owners to consult a certified Volvo mechanic for a comprehensive diagnostic to identify and resolve the underlying causes.