Hello, I'm sorry nobody has replied sooner, I hope I can offer you some assistance.
Did this concern only start after the service? Or did you have the van serviced to try to cure this? Are any warning lights coming on? Do you know what parts were replaced during the service?
Let me know and I'll reply as soon as I'm able to.
as this has started to happen since you had the fuel filter replaced then I would start with checking that the fuel filter is seated correctly and that the small drain on the bottom of it is tight.
It may be just a coincidence that this has occurred after the service. If the fuel filter appears OK then fit a transparent hose in the pipe between the fuel filter and fuel pump, run the engine and look for signs of air in the pipe. If there is excessive air in the pipe then you need to stop the air ingress.
If there doesn't appear to be any air then you need to have a scan done of the engine management to see if any fault codes are stored to pinpoint the sensor or actuator causing the concern. Any garage can do this so the cost is minimal. Normally when an engine management fault is detected you should see a warning light though.
Start with checking the fuel filter security and for air ingress and go from there.
Let me know if I can assist further or if you have more questions regarding this and I'll reply to you as soon as I'm able to. Don't hesitate to come back to me through this question.