@Isccsi,
I can't comment on the data you are passing to jqGrid, as I haven't used that jQuery plugin myself. I did notice one thing that could be a problem. You are using the SerializeJSON() function on your data, but you are also specifying the ReturnFormat on your function as JSON. Specifying the ReturnFormat causes the value being returned to automatically be serialized to JSON; thus, you are serializing your data twice (once by calling the SerializeJSON function, then ColdFusion does it again automatically when it returns the data). This may cause JSON to become malformed.
Since you are not returning your query directly from your function (you are looping through it and building an array of arrays), you shouldn't need the SerializeJSON call at all. You should be able to just return your stcReturn variable.
HTH,
Carl V.