misfire

My 98 Chevy 5.7 V8 is having a tendency of throwing a code going up long hills or when put under a load. Everytime the SES light comes on I will pull the code with a scanner and it's always P0304 - Cylinder 4 misfire. If I'm getting this every time can i just change the spark plug for cyclinder 4 and not change all of the others.

it could either be the plug wire, engine timing just off, a weak hydraulic valve lifter (or low oil pressure). this is what I hav ecome across recently with my '96 z71 with 240,000 miles.