Problems with spark plugs and wires
 

I recently replaced the spark plugs and spark plug wires https://mechanicfaq.com/spark-plugs-for-5-3-silverado/ on my 2002 Chevrolet Silverado 2500HD, on the way to autozone (approx. 4 miles away) to get my refund back for the warranty, the engine started a pulsing shake only when I idled in the parking lot. I knew it was a misfire and immediately thought I inserted the plug wires wrong. I took all 8 out and plugged them back in but it didn't help. I read the code P0300 which said 1 or multiple misfires,also a fuel pump code. I already had codes for my fuel pressure sensor, and knock sensor(which i was trying to avoid till I could afford it). The engine shake has progressively gotten worse to the point where I feel it while accelerating, and driving at a constant speed(losses power). My question to all of you, is what could cause a misfire after replacing spark plugs correctly? Could it be the fuel pump/pressure sensor causing the misfire? Or is it the coils? Is there a way to narrow down which cylinder is misfiring before replacing a bunch of other things? I just need the misfire gone so I can gradually fix the little issues. Any comments will help me greatly. I'm out of options other than replacing the fuel pump and hoping that's the main cause.
Thank you for your time:)

Re: Problems with spark plugs and wires
 

I would start with one of those spark checkers that go in line between the plug wire and the plug. That would tell you of a misfire and which cylinder right away.

https://www.amazon.com/Ignition-Diag...14912016&psc=1

Re: Problems with spark plugs and wires
 

yup that checker there will be your best friend. theyre at autozone also in the tool section

Re: Problems with spark plugs and wires
 

The one thing I always do if I have a problem with the things I have just touched is the common sense approach . In this case wires and plugs and a miss fire . The engine warning light on the dash should be flashing with a dead cylinder , not just on . One thing that can happen is crack a spark plug trying the get the old wires off and not realize it . They can be tough some times . Or the plug wires have a problem .

I would start with this before a fuel pump problem to be a suspect .

Also these newer gm trucks do not monitor fuel pressure or have a sensor . Not sure what your are talking about unless you are talking about the regulator on the fuel rail . Fuel pressure is pretty easy to check with a gauge on the fuel rail .