HELP! Inline 6 valve adjustments

[slow69]

Question for you sixers out there. I drove my truck today (haven't driven in like a year) and I had a noisy rocker arm so I took it back home, and pulled the valve cover. I noticed i had a bent pushrod, so I replaced it (actually both intake and exhaust). I snugged the rocker up so that the rod had some drag when I spun it.
I then started the truck and went about adjusting them all. I used the method of loosening each one until it clicked, snugged it until it stopped and then went another 1/2 turn. I did this too all of them and it didn't sound great and there was still a little tapping. It was coming from the first rocker arm (closest to the fan). It turns out the stud was bent, so I unbent it and put the valve back on. I adjusted that one and it was much quietter.

Ok, now heres the weird thing. The truck doesn't sound good at all. Before I drove it, I would start it up about twice a month and let it idle for a while and it sounded silky smooth. Now, it sounds like crap. I checked the timing, it was fine. So what is going on?