I intentionally started making kufr statements and started to belief in it and then said to my self this is kufr and rejected the statement which i was believing in and renounced it. Is my Islam valid?
If you are demented then your Islam is still valid. However, if you are not demented then no, it is no longer valid since you intentionally negated it; and you must renew your shahada.
Hajj Gibril Haddad