1991 Honda Civic DX, 1.5L, Automatic.
The last couple of months when started the engine has been running rough. And then even more rough when put into gear. Now that it has gotten colder it has started to stall as soon as it starts. Now I have to keep my foot on the gas peddle for a couple of minutes before I put it into gear so it won't stall. Once warmed up, it run great as always. Thoughts?

. Replace the spark plugs (NGK only), if they have not been replaced in the last 25,000 miles.

. Clean the Idle Air Control Valve:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-7.html#post1054149

. Check the Fast Idle Thermo Valve. Remove cover (two hex head screws) and ensure plastic ring, which goes around the valve, is rotated clockwise until it's fully seated--don't overtighten. If it's not seated, it allows in too much air, which the ECM keeps trying to adjust for. It's located under the IACV on the back of the plenum. It's hard to see, but it's there.

. Check/replace the Engine Coolant Temperature (ECT) Sensor, if the problem persists. The ECT Sensor affects fuel injector pulse width. It's located on the thermostat. It's a temperature dependent resistor (thermistor), whose resistance decreases as the engine coolant temperature increases. It provides a richer mixture when cold, leaner mixture when hot.