Yea idle RPM looks normal. We didn't mess with the AC belt at all. Odd that it would be having issues at the same time, you know?

I do think the bearing on the main drive/serpentine belt tensioner is going out. Was having a random chirp with the old belt and it sounded extra noisy when we spun it while swapping the belt. But no noise or anything now with the new belt ironically.

I seem to remember the VANOS all popping back in but I should recheck. Plugs where all tightened to spec and triple checked. No misfires or codes so I wouldn't think it would plug or coil pack related.

However, the local indy shop that just looked at it has me second guessing my selection of plugs (NGK 6441 Iridium IX). Got that recommendation here...but maybe my engine doesn't like them for some reason? Maybe they are gapped wrong? Need to post in a thread I found about them and see what others are using for sure.

I think I will buy and install some of the factory plugs (already trashed the ones I pulled out unfortunately). Just to make sure that's not the issue.

New shop was able to finally figure out the cause of my crazy vibration... and determined that I'm an idiot. :doh:
Turns out that when installing the lower left bolt back in the alternator, I missed the bracket that it was supposed to run through. I had to remove it in order to swing the alternator out of the way to get access to a bottom bolt on the left side upper timing case cover.

http://www.growfishtank.com/x5/IMG_0420.JPG

It was a PITA to get back in and after all that, it wasn't even right! Basically it was bolted back on one side only. Ugh...

But they also noticed that one of the engine mounts was toast - so replaced both of those as well.

Turned out to be a $800 amateur mechanic oversight... live and learn I suppose. After a month of banging my head against the wall, I'm just glad it's fixed!

She's smooth as silk now and I'm a happy man once again. :thumbup:

Any of us that have been DIYing for very long have been where you were. March on.

Congrats on a solution! Yep been there and done that....

Yeah, congrats. Now, if I told you mine … The lesson I learned is that the troubleshooting process should start with the simplest of the things you touched. In my case it was swapping the CPS connections, yep as simple as that and leading to weeks upon weeks of frustrations finding out reason for rough running and check-engine light. :D

Same here. But glad it was something quick and 'easy' to fix in the end and it's all running great! Thanks for posting the solution too!

Thanks guys! It's been a learning experience for sure lol

Yeah, the important thing is you found it and it didnt toast your motor. Good you found it, I know it feels great solving something like that!

Brings back memories of my frustrations post valve cover install. Glad you got it all figured out