The fuel pressure regulator is difficult to test without a pressure gauge. The removal of the vacuum line really doesn't change the idle much at all. On my B23 the fuel pressure regulator jammed up and the line pressure was hovering at 80 psi, regular pressure is 35 psi. Removal of the vacuum hose will affect the gauge if the regulator is intact and operating properly.

Anyway, I would advise the renewal of any old 02 sensors, and the mixture adjustment that is on the AMM, I advise you do not screw with it unless you have the emissions equipment to properly adjust it. IF the screw is way off, (it has no end stop) you might set it to the baseline setting. I can't remember it well but I thought was to tighten it down all the way and unscrew it seven full turns. "Adjustment screw has a range of 15 turns and lacks distinct end stops. Turning counter-clockwise decreases CO content. Turning clockwise increases CO content"[Group 23 Section 2 LH-Jetronic II, Page 29, Paragraph 1]

Increasing the CO will richen the mixture.

Note that this is also is for the 1983-1984 LH-Jetronic:
"Operation B24 Check Air Mass Meter. Connect ohmmeter between termials 6 and 7 and then 6 and 14. Resistance between terminals 6 and 7 should be 3.7 ohms.

Resistance between terminals 6 and 14 should be 0-100 ohms (resistance depending on CO-adjustment screw position)" [Page 26, Paragraph 3, Section 2(23) LH-Jetronic II 1983-1984]

I know that your car is different, but maybe someone else will share more relevant information. You should check the temperature sensor for your fuel computer, A missing signal will cause the engine to run rich as the sensor should have a negative temperature coefficient, meaning that as the temperature decreases the resistance also increases, a missing or misinstalled connector will tell the computer that it is approximately -48F .

You should also check that the throttle switch is properly adjusted (clicks when you open it the slightest), and is electrically intact. A defective connection or adjustment will heighten the idle speed as well, and may even enrichen the mixture.

In any event gentleman, I would advise the replacement of the 02 sensor, as Autozone sold me mine for my B23 for about twenty, and the fuel pressure regulator ordered from FCP should not be much more.

A merry Christmas to all!!!