MY CAR IS IDLING UP AND DOWN on 1990 Acura Legend

MY CAR WILL RUN, BUT IT'S KEEPS ON IDLE UP AND DOWN I DON'T KNOW WHAT CAN CAUSE THE PROBLEM CAN YOU HELP ME WITH IT.

Asked by for the 1990 Acura Legend
2 answers
Sounds like there is a vacuum leak somewhere at the intake manifold.
Check all the vacuum hoses, make sure they are not disconnected or broken.

Zee
As Zee said vacuum leaks are most likely the cause but low coolant level or bad coolant temperature switch also causes this surging idle.