Yes... Mark is right...  check that TPS (throttle position switch)...
either gump up and not working (need cleaning) - or defective (replace).
https://gowesty.com/products/mechanical-throttle-position-switch-tps-for-digifant?srsltid=AfmBOooFMiasWh0a6N_9vAaptsZZDIUa2Tr_YHt-PdNZL9ydf6O-ffKl&variant=41426747097253

On Mon, Apr 14, 2025 at 3:06 PM Mark McCulley <mark@markmcculley.com> wrote:

> Hi Markus,
>
> Your described symptoms are similar to what I experienced with my van
> about a year ago. The problem turned out to be the throttle position
> switch. This switch is located on the underside of the throttle body, it
> tells the ECU when the accelerator pedal is pressed (run state) and when it
> is not pressed (idle state).
>
> Good luck!
>
> -Mark
>
> > On Apr 12, 2025, at 6:55 AM, Markus Benne <mbenne@m-bass.com> wrote:
> >
> > My bus has developed an escalating issue where it it will bog while
> driving for a second, then keep going.
> > This has been going on for about a year, but it is suddenly much worse,
> to the point of the car actually stopping.    Usually it will eventually
> restart and run fine for a little while before recurring.  Frequency is
> increasing.
> > I needed a tow the other day for the first time, and I'm about to
> trouble shoot, but it was placed badly (couldn't open rear hatch), and
> although it started badly, it did start, and is now running fine.   Grrr.
> >
> >
> > Exhaust isn't blocked as far as I can tell ie exhaust is coming out.Air
> filter seems ok.Fuel supply next I guess.
> > Any input appreciated.
>