I HAVE TWO MISFIRES P0303 AND P0302. I have a mechanic that says he has a machine that can diagnosis the problem. I have another mechanic that says try tune up first

Here are my thoughts (FWIW) Diagnosis is always better than guessing!!!... Both mechanics may be right... However, maybe not!!!... 'IF possible'.... I like to know what's wrong before tackling any problem!

DIAG ALWAYS 1ST

Diagnose it first. It may be a tune up but would not rule out a coil pack either.

swap coil packs with the ones that are not coding and see if DTCs change to reflect the now affected cylinders. If they do then replace the bad coil packs