Code P0300?
 

Does this mean I should change plugs and wires? What other things could it be?

the code is a random misfire could be bad plugs, wires, vacuum leak, PCM. It can many things because multiple things can cause a misfire. Tell us the year and size motor and maybe a description, does it come and go or stay, is your truck running really rough, or anything else that can help us figure it out.

Its a 2003 5.3, it comes and goes, mainly when idling after im going down the road its fine

my 05 with a 4.8 same motor just different pistons,crank and rods has the same problem, i do not get a check engine light but when i tried to get a inspection it has this code, i also would get a pop thru the intake when taking off sometimes. i changed the intake gasket,this helped the intake leak.there are 2 different gsts i bought the most expensive one,i changed plugs and wires but still have random misfire.do not know where to look next