Is it obligatory to continue reciting the verse "Guide us to the straight path" even if the letters are pronounced incorrectly, in order to overcome the obsessive whispers regarding the articulation points of letters, knowing that correcting it leads to repeating the verse and doubting the pronunciation?

The cure for obsessive thoughts (waswas) is to ignore them and not pay attention to them. Therefore, you should read normally, without affectation or over-elaboration. Do not repeat your reading or heed the whispers of Satan. Continue with your prayer and reading, and know that the word "الصراط" (As-Sirat) can be read with a 'seen' (س) or a 'sad' (ص), so your reading and prayer are valid with either.