Figures I should look a the CD before talking. They don't use an old style warm up regulator for control presure on these engines. Looks like it is all managed with the EHA (on the side of the fuel distributor) and the diaphragm presure regulator. Just means that you have to check the sensors. Big one here is probably coolant temp sensor. Looks like it should be 2.5k ohms cold and 340 ohms hot (all readings plus or minus 15%).
Replacing vacumm lines can't hurt. As the engine ages, little vacumm leaks always creep in. You get enough of them and it gets beyond the ability of the lambda system to make up for them. Keep an eye out for gaskets going bad. You can usually spray a little carb cleaner along the gaskets and listen for an RPM change to spot where the gasket is bad. Sealing rings at the injectors are another place for leaks. Some folks just replace them to be sure.