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.