So my vacuum has been sitting at -13 for a while and I cant find the leak. I've been dealing with an odd boost leak as well. I ran a boost leak test yesterday and found a tiny leak where the bov meets the uicp. Tightened that down and it helped a bit but didn't change the vacuum. Vacuum normally reads -17 in my car. I have checked mechanical timing.

Things worth noting: My BISS is overtightened with the head stripped, courtesy of the previous owner. Car idles perfectly fine after a lengthy relearning process.
The boost leak is inconsistent. Today I was able to hit 24 psi without any issues. Yesterday I had a leak when I hit 20.9 psi and after that couldn't get over 15.5 psi.
The car is still fast, even when it can only make 15ish psi, but noticeably slower. Like I'll still eat up a mostly stock Evo X even when leaking.
I have checked and replaced my blow off valve (put the Turbosmart back on after I confirmed it worked fine), replaced the Wastegate Actuator, and inspected the turbo. My Truboost appears to be working fine.
I have inspected my vacuum lines as best as I can.

Does anyone have any possible things I can check or test? I don't have a smoke machine readily available but my friends shop would gladly smoke the car for me, I just hate going there as they never charge me and I feel bad. I will go there as a last resort.

 

Might have deeper issues then a vaccum leak.
You should do a compression test. Also attatch a vccum guage directly to intake manifold to get a second reading.

 

Ah, sorry I forgot to mention I did one just a few days ago. 171, 173, 173, 169. Good numbers.

 

Boost leak test-- you can make a tester, there is a posting on it somewhere. may want to check the TB with some carb cleaner while running as well---

 

So I decided to buy a new compression tester as the one I had been using was literally older than me and was giving around 170 on an engine I knew had low compression. Anyway... Cyl 1/3/4 all around 160. Cyl 2 is sitting at 70-75ish. A bit of oil in the plug hole bumped it up to around 100. So I think it's safe to say it is rings. The car is still driveable and not burning any noticeable amount of oil, so I'm going to continue driving on it until a motor pops up in my area. Old age and unknown service history can be a ***** for sure but it isn't the end of the world. Ran a boroscope in too and couldn't see oil washing the piston or anything thats a clear telltale. The low compression would explain my erratic vacuum. Boost leak is fixed.

 

That sucks. Glad you found the problem though.