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.