Ok now let's go back and take a look at a couple of things here. You have caused me to study

and study a bit I have. Further along than I had gotten to on my own as of yet (I am still only in Gen ;) )
Lets take a look at Exodus 7:3-4...and I am looking from Youngs Literal Translation.
This is before the plagues
7:3 And I harden the heart of Pharaoh, and have multiplied My signs and My wonders in the land of Egypt,
7:4 and Pharaoh doth not hearken, and I have put My hand on Egypt, and have brought out My hosts, My people, the sons of Israel, from the land of Egypt by great judgments;
So God hardened the heart of Pharaoh sounds a bit more like God was trying to touch the heart of Pharaoh in order to let the people of Israel go. And lo and behold it states the Pharaoh did not hearken...which means listen.
We see the same thing mentioned is Exodus 9:12
And Jehovah strengtheneth the heart of Pharaoh, and he hath not hearkened unto them, as Jehovah hath spoken unto Moses.
Otherwise all throughout this story it is the Pharaoh that has hardened his heart against letting the people of Israel go.
And as you can read that even with an influence of God the Pharaoh did not listen. So God did not override the Pharaoh's free will. This influence is no more so than what Pharaoh's own scribes have to state to Pharaoh in Ex 8:19 that "it is the finger of God". Even Pharaoh's scribes though could not influence Pharaoh.
Remember that Pharaoh had had enough of the Israelites and was prepared to let them leave before god worked his little trick. Free will? Ha!
And I have no idea where you got this idea from? Of which shows that you may not know of which you are talking about. The Pharaoh was never prepared to let the Israelites go...
First meeting of Moses and Pharaoh Exodus 5
5:2 and Pharaoh saith, 'who is Jehovah, that I hearken to His voice, to send Israel away? I have not known Jehovah, and Israel also I do not send away.'
And it even goes on to state that the work load of the Israelites was multiplied because "ye have caused them to cease from their burdens" Ex 5:4. And as punishment they were to make bricks from mud with no straw supplied...they would have to get their own straw.
Pharaoh was in no way preparing to get rid of his free labor...he was building himself an vast empire and monuments and great things in his name. He was not about to let his labor force just go free and away.
Again I state that God did not control Pharaoh or make his decisions for him. And the verses clearly state that even with an influence of Pharaohs heart the Pharaoh clearly exercised his free will and hardened his own heart against releasing the people of Israel. God wanted him to let Israel go...but he did not listen as the verses state.
Yes it does work, for if god is tampering with people’s minds and emotions then god is causing us to do things that we might not otherwise have done had god minded his own business. This affects our decisions absolutely and undeniably, and if our decisions are affected in such a way (especially without our knowledge or consent) then free will is largely a moot point, and perhaps like Pharaoh we are having tricks played on us too but simply don't know it. Impossible to know, true?
Then I propose to you to no longer read, watch TV, or do anything. Because everything you see, hear, smell, touch, taste, or feel can influence your decisions and thus possibly make you do something you would not normally do without any of those influences.
You attempt to pick and choose what influences are "tampering" with free will and which do not. A friend giving advice by your definition is removing free will. The directions a parent gives a child is tampering with free will. And quite frankly you are incorrect. An influence is just that...an influence. It does not ultimately control your decision. Your decision is still of your own free will. As even shown by the verses above even God's influence can be ignored...how? Because He does not control us, and let's us decide for ourselves. He does not make our decisions for us. Thus since our decisions are our own to make then we are not predestined/preordained... because those state that our decisions are not our own.