All perfect praise be to Allah, The Lord of the Worlds. I testify that none is worthy of worship except Allah and that Muhammad, is His slave and messenger.
You should know, dear Brother, that Allah, The Exalted, has made the Quran easy for His slaves, as He Says (what means): {And We have certainly made the Quran easy for remembrance, so is there any who will remember?} [Quran 54:17] Allah, The Almighty, does not overburden us with what is beyond our ability and capacity. The hardship you experience in this regard may be due to the exaggerated attempts you make to articulate the letters from their correct points of articulation while reciting the Quran in prayer. However, the Arabic letters are easy to utter and pronouncing them correctly does not require such exhaustion and shortness of breath. If you are able to pronounce the letters from their correct articulation points when reciting the Quran slowly, then you are obliged to recite slowly when performing the prayer individually. But, if you are in a congregational prayer, you should not be late, taking your time in reciting it properly. Instead, you have to follow the Imam because it is not obligatory on the one being led in prayer to recite Al-Faatihah according to the Hanafi and Maaliki Schools of Jurisprudence, as they are of the view that the recitation of the Imam is sufficient for him. This scholarly view is more convenient for you and those in your situation. So, there is nothing wrong in opting for this opinion as long as you cannot keep up with the Imam. This applies if you really find difficulty in pronouncing the letters correctly.
However, if this is merely prompted by satanic whisperings (Waswaas), you should ignore them and consider your pronunciation of letters correct. You can verify the correctness of your pronunciation by consulting someone who is knowledgeable of the proper articulation points and characteristics of the Arabic letters. If he informs you that you pronounce the letters properly, you should know that what you are suffering from is the result of satanic whisperings which you should totally ignore. However, if he informs you that your pronunciation is defective, then try to correct it with the help of this person or someone else if possible; otherwise, you bear no sin for it because Allah does not charge a soul except with what is within its capacity
For more benefit on finding hardship in recitation of the Quran while praying behind the Imam, please refer to Fataawa 354229, 352828, 211450, and 360037.
Allah knows best.