Cannot delete empty columns (below header) where pasted source data had "" as result

I have a macro that cleans up my data sheet in preparation to feed into another program. Part of this cleanup is to copy the source worksheet to a new worksheet then paste all as values to remove lookup values. A separate part of the macro then deletes all rows where the interior color is anything other than yellow (colorindex=6) AND there is no data below the header row. However, this is not working on columns where I previously had a lookup value that output "" when there was no value found.

I tried adding a code to clear all cells where value was "", however that killed performance and made the macro unusable. Is there a way around this.

These are the two blocks that are not playing well together:

'Copy and paste as values to remove lookup references

    Cells.Select
    Range("A4").Activate
    Selection.Copy
    Selection.PasteSpecial Paste:=xlPasteValues, Operation:=xlNone, SkipBlanks _
        :=False, Transpose:=False

'Deletes non yellow interior color columns where no values are present below header

Dim iiCntr As Long
Dim rwsToCheck As Long

Set ws = ActiveSheet
rwsToCheck = 5000
lColumn = 103
For iiCntr = lColumn To 1 Step -1
    If WorksheetFunction.CountA(ws.Range(ws.Cells(2, iCntr), ws.Cells(rwsToCheck, iiCntr))) = 0 And Cells(1, iiCntr).Interior.ColorIndex <> 6 Then
        ws.Columns(iiCntr).Delete
    End If
Next