P0304 code, It runs rough I have replaced the plugs, wires, distributor cap and rotor

Question

It ran great for about 2 weeks no misfires or other codes. Then one morning I started the truck and it now runs like it did before I did any repairs and throwing code P0304. Any ideas what to replace next?

Answer 1

P0304 Misfire number 4 cylinder

Use fuel injector cleaner the one that is added into the fuel tank, these type of fuel injector are famous for getting stuck closed. and causing random misfire are well.