you can, but with this many miles, and your presant problem, id worry about fixing the issue at hand first, then make a list of things to freshen up the motor first IE valve train, transmission, among other things, then start making a goal of what you want to get out of it before throwing performance into the mix.
These cars respond very well to mods, but you need to support those mods to make them relaible
Best bang for the buck is a 3.4 pulley, PCM, intake, headers or front powerlog, and downpipe, VS cam, with springs if you can swing it if not, springs, rods, and 1.9 rockers give you better power on a budget
