The first step is to confirm fuel pressures are in spec, along with fuel volume. While the gauges are attached and the engine is at warm idle, rev the engine- the pressure must not dip very very much. This tests that the fuel pressure regulator is doing it'd job , keeping constant pressure. ( you could have a blockage in the return line too)

Check that the throttle switch is closing.
Check the fuel distributor plunger isn't leaking.

I would also pull out the fuse in the OVP and see how it runs. This will test to see if its a electrical or mechanical problem.

You can mechanically set the mixture by reading the O2 sensor voltage.
Unplug the O2 sensor and read DC volts. Adjust the mixture screw so that the O2 sensor reads ~.45 volts dc fluctuating. between .1-1 volt.

At cold start does the engine rev ~1100 rpm then after 28 seconds settle in at 750?

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1993 2.6 Sportline 5 speed
1992 2.3 Canadian delivery