I know this thread is old now but I wanted to post a follow up for those that use the search feature.


I went to Autozone and free rented a block tester. The fluid turned yellow in seconds and confirmed I had combustion gas in the cooling system. Honestly, the rent of this thing was zero dollars and the fluid was about $5. Next time I have a misfire this will be the first test I do after checking in the dark for arcing. It was an incredibly simple tool/test.


I ordered a complete HG kit and proceeded to tear it down. It was actually incredibly easy. I will say, head bolts tightened to 15lb, then 90* and another 90*, are a heck of a lot tighter than I expected. I broke a Snap-on 5/8 6pt socket trying to get the first one loose. Impact sockets held up fine.


Once the heads were removed I could see that not only was there a very small break in one HG, but the #4 exhaust valve was broken. Ordered a new one; and lapped and installed it in about 10 minutes.


I did not get the heads machined. I have a very long sanding block and I just sanded them with 600 grit for a while. They seemed perfect actually before I ever started sanding, using a steel straight edge there was no gap that would make backlight visible.


Put it all together and it runs amazing. I say this is a DIY job, but I recognize that most people choose to machine heads, I don't own equipment for that.


I did not replace the wires or coils either. I don't think it's hard to remove the upper intake and get back in there if I need to later and I chose not to spend money replacing possibly good external parts. So I don't see the HG as a job like so many others do, as a "since your in there replace this and that too". But that's just me.


No trouble codes since.