G'mornin! To answer your last three questions, a little more information would be useful.
If the engine's running poorly, bogging down and failing to generate much power, then you might need a tune-up. You could consider plugs/wires/cap/rotor (always the easy stuff first). You could check the timing to make sure it's right, check the fuel pressure to make sure the new pump is running right, make sure the flow through the fuel filter is the correct direction, etc... You'd want to note whether you were losing power at idle, or at specific engine speeds, or only under load.
If it's an automatic tranny that's going bad, then the engine would probably be responsive; generating the right amounts of power, even when under load, but the power would just seem to be going nowhere. (At least that's what they tell me; I don't drive auto trannies...)
I don't have answers, I just try to ask the right questions.
Hopefully it's the right set of questions so that the more knowledgeable people here can get more info to work with. More intelligent people: feel free to chime in anytime.