2000 hi-ace GL gas ang car ko,

Last night I drove the car from fort to north edsa, avg speed of about 80km
then when I tried to slow down I noticed ayaw bumaba ng RPM,

kapag naka neutral naiipit siya sa around 2500 rpm

don't really have funds as of the moment to have it checked since my parents aren't around, can you guys guide me through the problem while I wait for money to have it fixed?