It will start but almost immediately sputters and dies. Can not keep it running. Gas pedal is hard to push down when trying to rev the engine a bit in park.

You may be losing fuel pressure or have a hard fault in the electronics of the engine control system. Do this, have the fuel pressure checked and have a fault code test run on the computer system. If all is ok then the ignition starter switch is suspect as well and the MAF sensor which will not set a fault when it fails.

You need to rebuild the carburetor or clean the choke linkage and make sure the choke valve closes cold.

Mass air flow , crank sensor . I wouldn't discount anything . Having a scan tool that can view engine sensor data would be a great help too , testing fuel pressure and flow and back pressure test the exhaust .
058 Engine Hard to Start or No Start Lean Fuel Condition
055 Engine Hard to Start or No Start Scan Data for EGR
057 Engine Hard to Start or No Start Ignition Module Test
007 Catalytic Converter Testing

does thr engine rev upwhen started than idels back down.try idel control switch and map sensor

Try having the cataletic converter checked. It sounds like thats the
problem to me.

Check the fuel pressure on the fuel rail on the injectors in the engine should read about 55lbs

The vehicle has a rev limiter. Will it rev over 3500 when you drive it? If no, then I would guess that the exhaust might be partially restricted. But the engine computer won't allow you to free rev the engine that high in park and neutral.

Check Fuel Pump

It sounds like your fuel filter is clogged. Try changing it.