Vintage Cars: w107 sl350 1979, airflow sensor, sl350

Question
wont start,taught fuel pump might be problem,replaced it... good spark...was getting harder to start in past few weeks like fuel restriction or lack of fuel pressure...can u shed some light..

Answer
I would look to the cold start injector and thermo time switch circuit
A cold start injector that fails to open is the same as the choke failing to close

Less likely
injectors
sticking airflow sensor
sticking control plunger

are you getting fuel to the rails?