Did you pull your codes before?
When you did the uim, did you replace the lim gaskets?

Your power brake booster may be leaking.

It'* definitely a vacuum leak, keep looking.

Exactly my thoughts too. If you didn't, and you have to get back into this project, I strongly suggest you replace those lower intake gaskets. GM now sells a real nice aluminum frame replacement for ~$60. Also replace the coolant by-pass elbow between the LIM and belt tensioner.

Sounds like a vacuum leak. If you have the patience, read this post about vacuum leaks.

http://www.bonnevilleclub.com/forum/...ic.php?t=49487

I got auto zone to read the codes when the UIM first failed, and got the random cylinder misfire. Went to Auto Zone yesterday, and they were so busy I left. As a test, I electrical taped the vac connections I could get to, and the idle seems to have improved tremendously! I will permanently fix them tomorrow. Havent been able to drive it yet, but the brake pedal seemed better as well.
Unfortunately, no, I didn't do the LIM gaskets. I read the whole 8 page thread regarding vacuum leaks and saw where the LIM gaskets fixed the problem - Oh great. Tensioner and coolant elbow are fairly recent. I am wondering, though, about the o-ring where the brake booster line goes into the UIM, as it comes in and out very easily.
Check engine light is still on, and I"ll get the codes read in the next few days. Dont those stay on for a while even after a problem is cleared up?

Thanks for the patience.

Yes, many codes will stay on for a few drive cycles after a repair.

As for the misfire, get those vacuum connections all repaired first, then see if you still have a problem before going further. It'* fairly inexpensive and quick to do that first and it often can be the only thing wrong. Just make sure you follow all the vacuum lines and replace all the rubber connectors, including the ones going to your evap. cannister.

replaced vacuum connectors today and its runs great. There was really only one that was very bad, but a few others came apart when I pulled them off. I tried the propane trick around the TB to UIM joint, since the gasket is visible, but it didn't change the idle.
Check engine is still on, but it runs great, and the brake boost problem is gone as well. Hopefully that will do it.

Thanks for all the help!

I had a mechanic buddy tell me a long time ago that at least 2/3rds of all rough idle and low-speed roughness problems are vacuum leaks. I've found that to be true over the years.

Glad it'* running well.

If that CEL doesn't go off soon, have someone read the code on it again.