Hi all for anyone who is interested I got the script created as follows:

--Code to pull out deltas between collected IO stats.

;WITH IOPS ([IO_STALL]

,[IO_STALL_READ_MS]

,[IO_STALL_WRITE_MS]

,[NUM_OF_READS]

,[NUM_OF_WRITES]

,[SIZE_ON_DISK_MB]

,[DBNAME]

,[NAME]

,[FILE_ID]

,[DB_FILE_TYPE]

,[DISK]

,[FILE_LOCATION]

,[TIMESTAMP]

,[ROW])

AS

(

SELECT *, ROW_NUMBER() OVER (PARTITION BY FILE_LOCATION ORDER BY TIMESTAMP DESC) AS [ROW]

FROM dbo.DISKIOPS

)

SELECT[IO1].[NAME]

,[IO1].[TIMESTAMP]

,[IO1].[DISK]

,[IO_STALL] = ([IO2].[IO_STALL] - [IO1].[IO_STALL])

,[IO_STALL_READ_MS] = ([IO2].[IO_STALL_READ_MS] - [IO1].[IO_STALL_READ_MS])

,[IO_STALL_WRITE_MS] = ([IO2].[IO_STALL_WRITE_MS] - [IO1].[IO_STALL_WRITE_MS])

,[NUM_OF_READS] = ([IO2].[NUM_OF_READS] - [IO1].[NUM_OF_READS])

,[NUM_OF_WRITES] = ([IO2].[NUM_OF_WRITES] - [IO1].[NUM_OF_WRITES]) --IO1.IO_STALL, IO2.IO_STALL, *

FROM IOPS IO1 JOIN IOPS IO2 ON IO1.ROW = (IO2.ROW+1)

WHERE IO1.NAME = IO2.NAME