Open .txt file
Start a loop:
    read each line into a string
    if the line starts with "id="
        take the rest of the string and do what you need with it
End loop

Dim ReqStr as string
Open <File Path/Name> for input as #1
 while not EOF(1)
  Line Input #1,Str1
  If  UCase(Mid(Str1,1,3)) = "ID=" Then
   ReqStr = Mid(str1,4,len(str1))
  End if 
 Wend

dim x() as string
dim y() as string

open "C:\output_file.txt" for append as #2    'open an output file where your IDs are stored

open "c:\testfile.txt" for input as #1    'open the file where are the IDs exist
do while not EOF(1)        'loop on line inside the file
line input #1,linee        'store this line in variable linee (don't write it line as it is a reserved word)

if instr(linee,"ID=")<>0 then  'check if the string "ID=" exists in the line,if it doesn't exist it will give ZERO , else it gives the order of the first character , <> means not equal
x=split(linee,"ID=")          'split the line containing "ID=" into 2 parts , one before "ID=" and another after it
second_part=x(1)             'you want the part after it , but it also contains the rest of the line " and some stuff"
y=split(second_part,"""")     'so split it into 2 parts one before the quotation """" and others after 
part_needed=y(0)            'your part is the first part before the quotation """"
print #2,part_needed  'write this part in your result file
end if                'end of if

loop                  'here the rest of the do while command
close #1              'closing input file
close #2              'closing output file

dim x() as string
dim y() as string

open "c:\output_file.txt" for append as #2    
open "c:\testfile.txt" for input as #1    
do while not EOF(1)        
line input #1,linee       

if instr(linee,"ID=")<>0 then   
x=Split(linee,"ID=")

counterr = 1
Do While 1

y=split(x(counterr),"""")     
part_needed=y(0)            
print #2,part_needed        
counterr = counterr + 2

If counterr > UBound(x) Then
Close #2
Close #1
Exit Sub
End If

Loop

End If
Close #1
Close #2