Volvo S40 power loss while driving
 

Hey guys, I had a problem last week when I went shopping and then went back to my car and it would not start at all. Two days later I tried to start it and it started like nothing happened.

Today when I was on my way to work, I was driving when suddenly I noticed that the acceleration pedal was not responding and the RPMs just went down and after 2 seconds everything was okay. One kilometer later it happened again and I put the car in neutral and the engine just died. I started it again and it was all right again.

After my work I put the car in the workshop and they told me that they had no errors in diagnostics and they were also driving the car like 40km long distance and they have not noticed anything.
Do you have any ideas what I can look for?
The fuel filter will be changed tomorrow and the fuel pump was already checked and is working normally.
I wanted to go home on Christmas which is 1200km from where I live now so I dont really know if I should risk it and go.
The car is Volvo S40 1.8 petrol 122hp year 2003.
Thank you everyone.

If this is a first generation S40 ( 1996-2003) then you could have rotten wiring in the loom under the radiator . worth cutting off the protective sleeving and examining them , look for swollen spots and green corrosion where the wires have turned to dust