Are you referring to the Ignition Control Module on the driver's side fender well that has 2 four pin connectors, CPS connector, and 1 vacuum line?

probably... I don't have that CD , but there has to be a vac line going to an Engine management module. That would be where to look b/c he is not getting Absolute Pressure from manifold communication...so the suspect would be a leaking vac line from the intake to whichever module monitors that vacuum signal. On 124, it would be the DM-N/59...I do not know where they get it on 201, but it has to be one of them. So, check all vac lines coming off intake, and specially one that goes to a module or vac sensor.

I think the ICM monitors the vacuum. Here's a photo, not my car but a good reference. You can see the L shaped vacuum line on the left side. I do know that if you unplug the vacuum line going to the ICM, the engine will still run but the RPM's drop.