What was the problem with Moshe's speech?

Rashi, Shemot 4:10 -"Heavy mouthed" - I speak with heaviness - i.e. stutterer

Rashi Shemot 6:12 - "Uncircumcised lips" - Blocked lips. And each use of the word "orla" (in tanach) means blocked.

Midrash Shemot Rabbah (Vilna Edition) Parsha 1 - "And Moshe grew" - ...and Pharoh would kiss and hug him, and he would take Pharoh's crown and place it on his own head, as he would do in the future when he had grown,...and the magicians of Egypt were sitting there and said, "We are afraid from this - that he lifts your crown and places it on his own head. That it shouldn't be him who will one day take the kingship from you." Some said to kill him, and others said to burn him. Yitro was sitting among them and said to them, this lad has no intent; Test him, and bring before him a bowl of gold and coals. If he extends his hand to the gold, he has intent and kill him. If he reaches for the coals, he has no intent and should not die. They immediately brought this before him, and he sent his hand to take the gold; and Gabriel pushed his hand and grabbed the coal and and placed his hand wit hthe coal into his mouth and burned his tongue. And from this he was made "heavy mouthed and heavy tongued."

Rashbam Shemot 4:11 - "I am heavy mouthed and heavy tongued" - I am not expert in the language of Egypt. When I was young I fled from there and now I am 80 years old. And we see in Ezekiel that one who is not fluent in a language of the kingship is called this (heavy mouthed)...(Ezekiel 3:4-6). Is it possible that a prophet who knew God face to face and received the Torah from God's hand stuttered?! And there is no reference to this in the words of the Tanaim and Amoraim. And one should not concern oneself with the external books.

Ibn Ezra - Shemot 4:10 - "Man of words" - (Moshe) knew how to speak clearly, his speech and words were not delayed and he didn't stutter, or that he had difficulty with specific letters...and one who says that Moshe forgot the language of Egypt is incorrect, as Moshe described 2 issues - "Heavy mouthed and heavy tongued". We also learn from God's response, "Who gave a mouth to man, and who placed a cripple..." that he wasn't referring to the language of Egypt. He was born like this ("heavy mouthed") that he couldn't produce all the letters of the lip and tongue. Only a few he produced heavily. and this is the meaning of "I will be with your mouth and instruct you." God said he would provide Moshe with the words that didn't contain the letters that were difficult for him to pronounce.

Shadal - Shemot 4:10 - The Rashbam already argued against the position that Moshe stuttered...and he says that Moshe was not fluent in the language of Egypt. And this too is not possible after growing up in Egypt in the house of the king. And the Ibn Ezra proposed that he was a stutterer and interpreted that "I will instruct you what to say" means that God will give him words that do not have the letters that were difficult for him. If so, Ibn Ezra should show us which letter are not found in the sections where Moshe speaks to the Jewish people. Aside from this being an insult against the heavens, that God would choose an emissary to give the Torah to His people who needs to choose the words which he can pronounce. And the truth is that Moshe was not a man of words, a man with the power of speech, able to embelish and extend language in front of anyone and not be afraid. This understanding agrees with why it is written about Moshe: "And Moshe was very humble, more so than any man on earth" (Number 32:3). And Moshe conceded that this was difficult for him, to go in front of a great king and argue with him after spending years as a shepard,

Drashot HaRan - But the essential matter is that it is appropriate for a prophet to be whole in all ways, that these are matters of honor in the eyes of the multitude, to elevate the masses because he is sent to them, and so that his words should be heard. And if so, how is it possible that Moshe should lack perfect speech? ...and the answer is that the Torah and its acceptance is the greatest thing that can can happen to mankind, and the nation that accepts it should be given strong instruction that it is true and all doubt be removed, that the Torah came only through the power of God...and this is the reason that Moshe was complete in all areas, to believe that his teachings are through the power of God; through complete divine providence clear speech was taken from him, in order that no one would think that the people of Israel and their leaders follow him because of his clear words. As it is known that it is said about one who is a great speaker that he pulls the hearts of the masses after him, and lies from him sound as truths. And this is the opposite for one who is heavy mouthed, as even the truth is not accepted. And this is why Moshe was heavy mouthed - with divine design, and not by coincidence. And this is why God responds to Moshe when he says, "I am not a man of words..." with "Who gave man a mouth and who made a mute or a deaf or smart person?" And this answer was sufficient for Moshe's question.