This sounds like a possible throttle position sensor issue. If it was, I suspect we have some codes so we need to start there. Here is a guide that will help:
https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing
If your engine has a Diesel then I suspect this is a UK vehicle. If so, that is slightly different then what we have here in the USA.
However, your throttle body is still going to have a position sensor and when they malfunction, you can lose throttle response.
I attached a number of documents below that will help with this. Does this happen often or did it only happen one time?
Please let us know what questions you have an what you find. Thanks
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Friday, June 25th, 2021 AT 6:42 PM