The warm-up pressure regulator is located at the front right of the engine. It has two steel lines and one vacuum. It has an electrical connection and is rectangular in basic shape.
Although trying another regulator is a choice, I would much prefer that you got a pressure reading off of it first. The best running cars have had their warm-up pressures modified to suit the conditions of the engine. I won't get into adjusting them untill you have some pressures.
The pressure that you should read is the one in the line that comes from the center of the top of the fuel distributor and runs to the warm-up reg. This pressure, which is a re-regulated partial of system pressure, opposes the movement of the metering piston working off the airflow meter. The higher the pressure the less fuel for the same airflow.
The pressure at cold temps is much less than at operating temp.
Bosch Master, ASE Master, L1
33 years MB technician