Q:

Who spoke to Pharaoh?

Shemot 7:2 states that G-d told Moshe that Aharon would speak to Pharaoh. Rash"i further explains that first Moshe should relate to Aharon what G-d told him, then Aharon relays the message to Pharaoh.
When we look at the later verses prior to nearly each plague, G-d tells Moshe "Go to Pharaoh and say to him..." He seems to be telling Moshe to directly talk to Pharaoh, not Aharon.
Also, when Pharaoh calls Moshe and Aharon back to remove the plague, it seems like Moshe is answering Pharaoh, directly.
Another "puzzle", here - In Shemot 7:17, the speaker says, "Behold I will hit with the rod that is in my hand on the Nile waters and they will change to blood."
We see later in verse 19, that Aharon uses a rod (it's unclear if he used Moshe's rod or Aharon also had his own rod, which he used) and it is Aharon that strikes the rod, not Moshe. If Aharon was the one speaking to Pharaoh, then, what he said seems consistent, assuming that he also had his own rod, or if he was holding Moshe's rod when he spoke.
I'd like some clarification on who spoke to Pharaoh and when? Did Moshe ever speak to Pharaoh? Or was it that Aharon spoke only to tell him the message about an upcoming plague. But, to remove the plague, Moshe spoke to him? 

A:

R. Avraham ben HaRambam mentions in his commentary (7:1) that according to some commentators, such as R. Sa'adya Gaon, Moshe was healed of his impediment at some point; possibly while still in Egypt, as suggested by the fact that an interlocutor is not mentioned in his communications. He cites Ibn Ezra, however, who writes that Moshe was never healed, and he always spoke through Aharon, although the Torah frequently doesn't say that his speech was indirect.

There are multiple ways to read Exodus (7:17), so it isn't a proof one way or the other about whether Aharon always spoke for Moshe to Pharaoh. Although the implication is that the one speaking to Pharaoh would strike the water, and the later verse (7:19) implies that Aharon was to strike it, we are not forced to conclude that Aharon was the one speaking to Pharaoh. Earlier verses (7:14) imply that Moshe is being spoken to; not Aharon. Accordingly, the instruction to tell Pharaoh "I will strike the water" is understood by HaKtav V'HaKabbalah (7:17) as meaning that Moshe said that he would cause the water to be stricken (by Aharon). This is the understanding of Paneah Razza (Parashat B'Shalah s.v. umat'kha) as well.
Alternatively, Ibn Ezra reads 7:17 as stating that God will say that he will strike the water with the staff in His hand! That is, that God will strike the water through his messenger's holding the staff. Accordingly, there is no evidence whether the speaker is Moshe or Aharon. R. DZ Hoffman follows this reading as well.
Additionally, although Moshe was instructed to tell Aharon to strike the river, 7:20 says that Moshe and Aharon did what they were commanded, and then the verse speaks of hitting the river. On this basis, R. Yitshak Abravanel (Parashat Vaera ch. 7 s.v. Vayomer) suggests that they both struck the river. Thus, in telling Pharaoh that "I will strike the river", it possible that Moshe was speaking of himself.
Thus, 7:17 is sufficiently vague that even ignoring Ibn Ezra's read that it is God who would strike the river, we have no proof for who was speaking to Pharaoh. It could have been Moshe saying that he would strike it himself (as per Abravanel), or it could have been Aharon saying he would strike it himself. Or it could have been Moshe saying that he would strike it through Aharon (as per HaKtav V'Hakabbalah) or it could have been Aharon speaking for Moshe saying that Moshe would strike it.

