Not performance related, as least as far as I could tell.

Knock sensor, two misfire codes, MAF sensor and cat converter.  I changed the plugs. Would changing out the MAF, knock sensor or coil as recommended make any difference in mileage, etc.?

It may depend on how the knock sensor has failed but, they CAN detrimentally affect performance by causing the car to over-retard timing.

 

many people have found cracks in the knock sensor and had good luck with $15 or w'ever replacements. pay attention to which direction the cable 'points', remove old sensor, clean underneath , bolt new one on, don't overtorque it, plug it in.

I bought a MAF sensor online.  Emissions test is coming up.  For a 1997 2.5 the requirements are lax.