[304065]

Remove the throttle links as I have explained above, then repeat the test.

With the engine at operating temperature, 180F oil temp, you say it runs fine? Then what is probably happening is the hot oil is heating up the MFI pump housing, which in turn is heating the thermostat, leaning out your mixture so the plugs dont foul up and kill the engine.

Remove the throttle links and lean the idle mixture adjustment out six clicks to the LEFT. See if you can get the engine to idle at operating temperature with no linkages.

You can remove the TBs to set the stops on a flow bench, the advantage of the 72 style is they can be more easily adjusted on the car. But I wouldn't go to the trouble of moving them until you first find out whether the correlation can be balanced at idle with the air screws. If it cannot, the TBs are either worn out (more likely, they are 36 years old) or some PO has moved the throttle stops. That is a fairly simple DIY flow bench operation with a shop vac and your synchrometer.