It starts and runs for three minutes and then.

What is the idling speed before it stalled?
Does feathering the throttle prevent it from stalling?

This indicates it is not a fuel metering or idling problem and could be an electrical problem. Check the ignition coil and distributor.

IGNITION COIL RESISTANCE CHECK

Set an ohmmeter in the low scale. With ignition switch turned "OFF", and coil wires disconnected, attach ohmmeter leads to primary terminals of leading coil and then trailing coil. Primary resistance should be 1.22-1.48 ohms for each ignition coil.

PICK-UP COIL RESISTANCE CHECK

1. Set an ohmmeter in the x100 scale. Turn ignition switch OFF". Disconnect connector between ignitor and distributor. See Fig. 4.

2. Connect ohmmeter leads to leading terminals and then to trailing terminals. Resistance should be 600-700 ohms at 68° F 20° C) for each set of pick-up coils.
If not, replace pick-up coil and bearing assembly.

IGNITION TIMING

NOTE:
On vehicles equipped with automatic transmission, block the wheels and place selector lever in "D" position.

1. Warm engine to normal operating temperature. Connect a tachometer, then connect timing light to leading (lower) spark plug of front rotor. Start engine and run at idle speed.

2. Aim timing light at timing indicator pin on front cover and check ignition timing. Rotate distributor to correct timing, if necessary. Tighten distributor lock nut and recheck timing.

3. Connect timing light to trailing (upper) plug of front rotor. Start engine and check timing. If not correct, loosen vacuum unit attaching screws. Move vacuum unit in or out to adjust trailing timing. Remove test equipment.

IDLING SPEED

1. Switch off all accessories. Remove fuel filler cap. Disconnect and plug idle compensator tube at air cleaner. Connect tachometer to engine. Ensure parking brake is engaged and wheels are blocked.

2. On air conditioned models, make sure throttle opener does not keep throttle lever from returning to stop.

3. Warm engine to normal operating temperature. Place automatic transmission in "D". Check idle speed. Adjust curb idle speed to specification by turning throttle adjusting screw.