Motor interruptions and shocks
 

My Olds Intrigue 3.5L engine, with 250000 km, has interruptions, shocks at any speed when driving.
Last thing that I fixed was a pipe from the steering pump. A few days later three dash lights came on, SERVICE VEHICLE SOON, PCS and TRACTION OFF. In the same time the engine started to have interruptions at any speed. It happened to cut off twice, to stop at 100 km/h and at 20 km/h, what I think should never happen. Could be the gas or a sensor?

Thanks,
ob