Hi, Nightshift.
The chord you'e talking about could be a G9(sus4). It could also be a partial Am13: ACGF

Just as two disembodied chords in the key of F, I say probably Am13 because Am is in F major, so the A with its third would make the ear hear a minor. The third generally provides the color that makes a chord sound major or minor, and the G9(sus4) reading doesn't have a third. And of course the key of F doesn't include a G major chord.

However, it really depends on the whole chord progression. Am is in the key of F major, and especially with the extended chord notes, it could be heard as a dominant of D minor--F's relative minor. If the progression went next to Dm (or D major for that matter) Bb or back to F, it would be an Am13 for sure.

However, if the progression went to C, the V of F major, you'd be right that it's a G9(sus4). G9 is the dominant of C, and the suspended C note could be seen as an anticipation of the root of the C chord. It would be a secondary dominant at that point, and the ear would hear it used that way.