Yes, I noticed in the first picture.

Also to check, there is a hose from the intake manifold plenum to a squarish device atop the injection pump. This squarish device is called the ALDA (German acronym for alitude and/or pressure compensator). The ALDA resists the IP's natural tendency to provide fuel for a max boost condition. The ALDA's influence is reduced as pressure in the intake manifold increases. The ALDA has to get a good boost signal from the manifold or the IP will think there is no additional air and not provide additional fuel. Make sure the line from the intake manifold to the ALDA is clear. There might be devices along the line. Those devices should allow air to flow freely as well. Don't forget to check the nipple on the manifold. It takes a 12mm wrench and it tightened to a very light torque. I've had no problems cleaning the line with brake parts cleaner.

On that subject, any tar you find in that line coats the inside of the intake manifold. You can thank EGR for that. At some point you will be advised to disable EGR because it's hurting as much as it's helping. The vacuum controlled wastegate complicates disabling EGR since EGR function is one of the ECU checks before allowing boost.

Sixto
87 300D