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I have a 2002 Honda Civic Ex Sedan with manual transmission with over 200k miles. It runs great. The only thing that I've noticed is a slight jerking when pressing the accelerator gently, so I always just make sure I'm either all the way off the pedal or accelerating hard. My CEL comes on from time to time and it gives me a P0300, P0301, P0302,P0303 and P0304. I just replaced the spark plugs thinking that could be the problem, but it still gives me the misfires. I want to check the fuel pressure, but I don't know where the test port is. I will do a compression test on it tomorrow, hopefully its not that. What should be my next step after testing the fuel pressure and cylinder compression?

 
Rep Power: 242

What plugs did you put in? NGK Iridium? Did you check the gap?

 
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I did use NGK. I did not check the gaps. I thought they came pregapped.

 
Rep Power: 242

They do but I have had them be off before. The ones I put in my GTI not to long ago needed adjusting.

I'd check that before checking fuel and compression.

 
Rep Power: 223

Does yours have EGR? The EGR runners are known to clog up and cause misfires in all cylinders.

 
Rep Power: 221

this would be my guess too