My Pontiac dealer told me the filter has been discontinued
1984 FILTER, power brake booster 17070814 N.L. 1985-88 FILTER, power brake booster 17085016 $7.70
Try the 1984 filter. I bought the 84 filter on 02-16-95 for my 85 GT for $11.83 + tax.
From: Scott Backer
I paid $9.95 for one of those "HELP!" filters, in 9/96.
From: Sketch
Where is the power brake booster filter location on a V6 Fiero?
It's pretty well hidden. The easiest way to find it is to take off the decklid.
The second easiest way (and stuff which you'll still need to remove if you want to reach it easily) is to remove the air cleaner to intake hose and the black pipe that plugs from the front rocker arm cover to intake hose.
The easiest way to find it is to find the pipe that sticks out from under the plenum towards the front firewall and put your hand on the hose that is attached to it. Follow the hose with your hand to where it goes on the firewall. It is attached to the power brake booster filter.
The easiest place to actually see it from is towards the left-hand side of the car, look at the front firewall from an angle through where the air intake hose you removed goes.
I think you may be able to get it out without removing anything else, but mine was brittle and hard to get off the hose, so I had to pull off the 'large tube which doesn't hook to anything/small tube which runs from the EGR solenoid to air cleaner' which is held to the firewall with 3 10mm bolts (the one left over from the so-called fire recall).
Back on the brake booster filter, the (almost) local Pontiac dealer said it has been discontinued, but they all work the same so you could probably find a different one which would work. I went down the street to the parts store and they had a "HELP!" power brake booster filter which looked exactly like the one in my car for $9.95. How convenient.
From: Sketch