"...I did my PCV and my car only had two lower intake manifold bolts. Of course I dropped one and can't find it. Could that cause a significant vacuum leak if all of the top ones are tight and the bottom ones are not?..."

Absolutely. Get all the bolts in place and snugged-up, then see where you stand.

I'm not familiar with 850's but is that $150 hose preformed in a shape that you can't use a piece of standard vacuum hose, or a preformed hose from another car (Chevy/Ford/Mopar) that bends the right way? Sometimes you can get a parts person at the local auto parts store that's a bit adventuresome and will search the shelves for something that will substitute for a fraction of the cost.
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Current rides: 2005 Volvo S80 2.5T, 2003 Volvo V70 2.4NA, 1973 Volvo 1800ES (getting ever closer to road worthiness)