Posted a thread on here about a P0301 code. Checked and fixed everything topside. Pulled the intake just now. Look at the cylinder one gasket. Also 5 out of the nine bolts were loose. Like finger tight no tools needed to get them out.

 

Posted my findings last year with the same issue, good find. I had a 100,000 miles on mine at the time, so I figured what the heck and installed new injectors since I had the manifold off. Really wonder how many people have had the same issue is why I brought it to light. I had two bolts tight the rest where either all the way backed out or finger tight like yours.

 

Problem not so solved. Put it all back together and went for a test drive. After about 75 miles of in town and interstate driving my code came back. P0301 pending cylinder 1 misfire detected.

 

If everything topside was checked, coil pack, plug, o2 sensors, cat, I think I would check the injector. I don't think that's a random misfire code. I think it is specific to cylinder 1. I think.