On the carbureted engine, the choke it likely closing too much AND not opening as it should, as the engine warms up.
It's likely an electrically heated choke housing that heats a bi-metal spring which pulls the choke plate open as the spring heats up. The electric choke housing will have power to it whenever the ignition is on. A first check is to see if there is power on the choke power wire. Pull the wire off of the choke housing and test for 12-volts (or use a test light), from the wire to ground, with the ignition key in the RUN position.
Sample 4-bbl Rochester carb with electric choke. Choke housing is on the left in the photo. If you have a 2-bbl, it will look different, but the choke housing will be similar.

Let us know what you find, and we can go from there.
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Gordon Arnold
New Hampshire
2003 268 Vista ..................................................................Prior: 97 245 Sundowner
