[MIT]

I have '74 914 1.8L with original FI system.
The engine have rough idle and I thought it's because of the air leak from vacuume hoses. So I changed all hoses last week, however it still have that symptom. Especially after engine get hot (i.e. after get off from the freeway),idle goes down to about 100rpm. The idle speed adjustment is already all the way to the right. Is this symptom relate with an airflow meter?
Please give me some advices?

Thank you.