The blow test is not 100%.

On my 200 ( I know you wer looking for 900 guys)...I had slow leaky seals and I could easily blow through. After pulling and cleaning the Separator leaks went away.
I did pull teh intake. it's seemed easy on the 200. all teh gas lines stay connected. Unblot the Intake and rock it up.
Removing that manifold keeps you out of trouble. the Heater hose needs to be persuaded a bit and you can't see that with the manifold in the way.
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'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.lyse.net/brox/TonyPage4.html

If you do remove the manifold, buy a manifold gasket
for a good seal.

A 1995 oil trap probably needs replacement just for age. I've replaced two which had holes in the top. The plastic doesn't last forever. When an oil trap has a hole in it, you smell a distinctly hot oil smell in the car when the engine is running, and especially with the hood up.

As Herb wrote, you don't need to remove the intake manifold, although you may find it easier to replace the oil trap if you do. I don't remove the intake manifold, even to replace the late style oil trap. Two 12mm head bolts hold the oil trap in place. If your car has EGR, you'll have to remove the EGR tube and then remove the nut on the EGR valve to move it out of the way, in order to access the two 12mm bolts.
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john

I would suggest you take the time and remove the intake. It is not that complcated and gives alot of room to work and prevent mistakes. Read up on the procedures and cautions. You will have access to a number of hoses that you should likely replace, including the heater hoses. There are many cheap parts you can take care of and learn alot about the top of your engine
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89 240 Wagon 217K, 94 940 185K

He's giving you good advice-- a clogged oil separator box is probably the #1 cause for rear main failure. In fact, replacing it will sometimes stop the oil leak (my '92 945T hasn't dripped on the driveway ever since I cleaned the separator).

You can remove the separator box with the intake in place-- I've done a few. I used a bunch of extensions and a universal and worked from between the intake runners from above. It's only 2 bolts (12mm, I think).

I have found that it is easier if you remove the idle air valve and the throttle body to give yourself more room to work and better sightlines. It's also a good time to clean both.

You can either clean the old oil separator box (which takes time) or replace it (there have been complaints about the quality of aftermarket parts). In either case replace the o-ring.

Good luck!