Ok, here is the deal. I did a tune up on my 07 tahoe 5.3L yesterday. Ever since it has been misfiring. I checked the gap on the plugs and they are all correct according to the service manual (.040) and I also replaced the wires. I figured it was the wires as it happened after I put those on. Reinstalled the wires twice, same issue. Even went and bought another set of wires on the off chance that I got a bad one in the last batch, and the problem is still there. Also I keep getting a snapping sound, like electricity is arcing but I can't find the source. Any other ideas?

 

Find the snapping sound and find your problem. You could stick your hand in there and feel around until you get bit how ever that hurts. Once it gets dark you should be able to see it. Why did you replace the plugs? What brand plugs did you use?

 

I replaced the plugs because it has almost 100k miles on it. Old plugs had a gap of .053. I have actually had my hand in there while it was running, pushing on the plug wires to make sure they were seated correctly, no shocks to me at all. I had it running last night in the dark (completely pitch black) and I didn't see any light shows either. The old plugs were original ac delco iridiums, so I replaced them with autolite iridiums.

 

If the problem was not there before you put in the plugs and wires and did not change with the second set of wires then try putting in the correct Ac Delco plugs. Sometimes the non OE plug just does not work even if it did work for someone else.

 

Just asking. Are you sure you didn't mix up one of the wires with another one? Very easy to do.

 

if you can hear it arcing then you don't have a connection fully seated, since looking in the dark didnt seem to work you may try getting a spray bottle and lightly mist over everything, or a bit more time consuming but you'll verify if the wires are good get a test light and hold it just barely over the plug wire and go along the whole wire, if the wire has a bad spot it'll arc to the test light

 

Wires are almost impossible to mix up on a car with coil packs lol. As for not being fully connected that wasn't it either.

Finally found the problem. One of the brand new spark plugs I had installed wasn't working properly. Problem solved...... I always forget to check new parts lol, I tend to think they should work properly the first time.