Engine problems
 

So recently my engine has had a rough idle and has even stalled on me. At one point it would not even start. To fix that I cleaned the throttle body and it started and ran strong like it used to. But now I am back to where I was. I checked to TB and it was spotless.

I recently purchased seafoam and am planning on using it within the week. I am thinking that there is too much gunk in the engine for it to run the way it's built to..... But if this doesn't work I don't know what else there is to do. So if anyone has had this issue and fixed it. Please tell me how

Also the engine has 172xxx miles on it and no check engin light on

It has a higher sound when revved then the deeper purr it had when I got it

It will sit at a lower gear and higher rpms without shifting when accelerating unless I really floor it and I'm just not seeing the same power I saw when I got it (bought at 169xxx)

Any check engine lights? Might need a tune up, spark plugs, wires, cap, rotor.

No check engine light, checked spark plugs they are relatively new ... The wiring might be an issue as there is acid erosion all over the terminals on top the battery. my mechanic told me that everything looks fine... I might go get second opinion though. Also it was tuned up and oil changed and all this past January.