One cylinder head dirtier than other

[89broncodude]

Long story short, I just changed my egr tube and was about to start putting the upper intake back on when I thought I would make sure my FPR was on tight enough. That's when I dropped my Alan wrench down one of the runners....like a ******* I didn't cover the lower intake up lol. 

So I pulled the lower Intake out to retrieve that little bastard and I decided to pull the valve covers to clean/change gaskets. That's when I noticed that there was a large amount of build up under the P/S valve cover and the valves were extremely dirty. However the D/S was extremely clean. Like suspiciously clean...

Any ideas? Bad headgasket?

Thanks  for helping a noob. Bought my bronco almost 2 years ago and havnt looked back since

 

[miesk5]

Yo,

As a guess, PCV valve is on passenger side.