Misfire

I changed the plugs about 6 months ago . And I checked the plug when I took it out . I hooked it up grounded the plug it fired fine. Could it still be the plugs

Could also be fuel injector related. If you got a P0302 code, it might be due to a fuel injector, cam follower, valve spring, intake or exhaust valve, cylinder head gasket, spark plug/plug wire or a COP. After the plug/wire/COP a fuel injector would be the next easiest thing to test.

Well I'm getting all new coils and plugs one day this week. Hopefully that will fix my problem. If not I have no ideal what to do . My injectors are new to. I want to add this little info to I put a plug on and grounded it and it was arcing. Looked fine to me but put the wire back on code reader still said 5 misfiring. Any suggestions please

Let me start over from the begining. I had to change my starter. Before that it ran fine . Since I got it back together I have put new injectors,plugs and coils on and it still missing . The code reader says my number 5 is misfiring. I checked it pulled it off the plug put a plug on and grounded it it was firing fine. I don't know nothing else to do