Wavering idle, poor vacuum

Hi, I have been getting a rather poor idle, it wavers between 500-600 rpm fairly rapidly and causes the motor to shake lightly when it drops down to 500ish range. My aftermarket boost gauge only indicates about 12 Inches mercury for vacuum.

I am aware that I have an ACC problem, vents/ac/heat cut out when in boost. Could this problem be related? Could air be leaking in from the ACC system?

I'm running on a fresh rebuild, new vacuum hoses, cleaned the AMM.

I really want to install my new V cam, but want to get this squared away first cause I know that will only make vacuum worse.

Make sure you don't have any vac leaks. Ya can kinda check your AMM by unplugging it. That ought to make your car run really crappy. When ya plug it back in, it ought to run regularly.

If everything else is working properly (might not be the case), you can up the idle by turning the big thumb screw on the throttle body.

you might have skipped a tooth on your cam or crank.
Check your timing marks

read the brickboard faq to fix your acc problem, just did this on my 940. it shouldn't affect idle/vacuum though. More likely timing or vac leaks as mentioned.

Do a quick check for a vacuum leak in the engine compartment. Buy some carb/ throttle body cleaner, and spray anywhere there's a connection around the intake manifold or hoses going to it (if a turbo). If the idle changes at all, you can find where your leak is.

Good info on vacuum problems here:
http://www.autospeed.com/cms/A_2393/article.html?popularArticle

I had a slightly milder issue with a faulty distributor...

also, like the other dude said...mechanical timing might have skipped a tooth or something (unlikely) but if you want to swap cams I'd go ahead and do it, that way you will know timing is 100% before diagnosing this problem. I'm pretty sure it's electrical..