What could cause the check engine light to come on during cold weather start? on 1990 Subaru Loyale

Have to keep foot on the gas pedal for several minutes to keep it running until the check engine light goes off.

Asked by for the 1990 Subaru Loyale
Have it scanned for codes.
Thanks. I understand that. I was just trying to see if anyone else has had a similar issue and what they might have replaced.
GUESS= coolant temp. SENSOR. Scan test will find out. Needs to be performed with eng. cold.