If you can identify patterns in text strings that are replaced by other text strings, you can use the Substitute command to reset them to their original values. This may help address the common, simple substitutions but you'll need to keep an eye out for situations that you have not (yet!) encountered.
All the best,
Thank you jim,
the problem is that I pass to the "Insert From Url" Script step, %2B but it's send to the server a "+" charcter ("+" = %2B if url encoded) that is uncorrect, I really need to send to the %2B.
It's to late to use the substitute function since it's the last step from FMP to the web server that receives the http requests.