Rule reminder
'Quasi che' + subjunctive is a literary modal connective meaning 'as if / almost as if', similar to 'come se' but more formal. 'Quasi' alone can precede a subjunctive in formal Italian: 'quasi volesse dire = almost as if wanting to say'. These appear in literary and journalistic registers.
Si fermò un istante, ___ stesse cercando le parole giuste per rispondere.