lol, that seems to be everyones answer to any 3.1 question. They really must be known for going bad...

LIM Gasket is changed out!
 

Hey guys. I just got enough money saved up to do my lower intake manifold gasket. It wasn't hard, just an ass-ton of bolts to remove to get where I needed to be, lol. Anyway, the new gasket is in place, even though the other one didn't LOOK bad. I swapped out my manifold and plenum while I was at it since the other one looked like it had caught fire on the inside. I tightened up my rockers and tossed in a new thermostat. As a result I no longer have any check engine codes.

I'm still running into an occasional power loss still, lifters still tick like hell (whatever), and my temp gauge still rests pretty far to the left (low temp). Only after driving a good distance then letting it sit idling for a few minutes can I get it to rise temp to the center of the gauge. I notice most of my power loss when the gauge is hotter.

I think from everyone's recommendations that the cat should be replaced. I have a 2.5" high flow from Catco sittin' around I can toss in there. Does anyone have negative experiences with high flow cats on these cars? Some cars respond unwell to less back pressure or different exhaust velocity. Anyone have a recommendation or personal experience with this mod?

Power Loss Problem Resolved.
 

As it would turn out I tried pretty much everything except checking my tranny fluid. Probably should have check it, since I was about a pint low. I added some fluid and vavavoom! She seems ok now, but I've only had it goin' for about fifteen miles with no signs of problem. I've got a few hundred miles I need to put on her in a few days. That should tell me for sure.

Although I still have really low temperatures for a car that feels like it's running hotter than it should be. Anyone have any ideas for this? Where does the needle rest on most 5th gen Monte's?

My needle rests a little below half way at its hottest and about 1/3 of the way while cruising down the road.

Hmm. Even that would seem weird to me, but I'm really low on the gauge. I might take a picture to better illustrate the positioning.