I have a problem with the van, which only occurs at lower speeds. When the RPM is low and I drive slowly, the engine starts stumbling. Why is this occurring? How serious is the issue?
It may be at a particular throttle angle and the EGR valve is getting carbon into the valve causing the erratic idle. You may need to have the engine decarbonized. If you hold the engine in neutral and REV it to 2500 rpms for a few minutes to see if the carbon is cleared. Have a mechanic check the engine for codes and diagnose the hesitating issue firsthand in order to have this corrected.