Will a tune-up fix my car's weak engine problems?

Hi, I have a 1993 honda integra. The engine was weak and struggling to get up hills in 1st gear. I had the muffler and exhaust replaced (it was damaged) and had some 'engine sump' secured (what is that?).

Alot of the power came back but still doesn't seem to have the power of 6 months ago. I went on a 6 month holiday and the car was not driven at all.

Will a do it yourself tune-up bring my car back to life?

Could it be any other problems?

Thanks