I just can't seem to fix this problem, I have a 1991 Civic with a SOHC ZC swap in it done professional. Just recently this winter I have been having a problem starting it in the cold or sometimes on a cold morning. Most of the time it fires first crank but then stalls right away. If I have my foot on the gas slightly and start it I can hold it at idle until it warms up a tad bit then I can take my foot off the gas and it will idle normal. Any ideas? Thanks

Start by changing the plugs... then the fuel filter... clean your injectors... make sure the air filter is clean... if it still missbehaves... you better take it to your "professional"... it might get expensive:(

. Clean Idle Air Control Valve:

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

. Check Fast Idle Thermo Valve.

. Check Engine Coolant Temperature Sensor.

The link below may help with these issues:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-46563-7.html#post842969

. Set idle speed to specs.