The washer tank comes out with like two bolts. Remove them and slide it forward or just remove it completely. Theres a plug-in for the pump motor and a feed line at the bottom that are easy enough to undo.

Actually, the washer reservoir has to come out in order to remove and install the fuel filter.

 

JM - if the fuel filter doesn't help, start a new thread with full info on the car and the problem you experience.

and scan the ECU for 'pending' codes.

 

my fuel filter since my car is "bucking" and struggling when I accelerate

That's not going to fix it, I can guarantee it. On average daily drivers Subaru fuel filters last the life of the engine. Unless the gas lid was left off, it was flooded, it's 30 years old, in the rust belt...it's not the fuel filter. And if it is you need to pull the fuel pump and clean the pump side filter off as it'll be more clogged than the filter.

Scan the OBDII codes - what numbers do you get?
is the AT light blinking?

Some of those early H6's would have TPS issues. it's the only 'common' (it's not very common) sensor issue on that engine. swap it with a used one. i can mail you one for a few bucks, message or email me.

they don't fail often enough to warrant a new Subaru one.

back to the fuel filter which doesn't need to be replaced:

I'd just manhandle it and pry and leverage on it with a large screw driver and make it pop out from behind the washer.

if you're not in a rust prone area you can unbolt the washer tank - you don't have to disconnect lines, electrical connectors, just unbolt it so it moves.

if you're in the rust belt those two washer tank hold down bolts shear off all the time, so don't touch them.

 

^^^^ good info on the tank bolts, never see that level of rust here.

has it 'bucked' over more than one tank of gas? maybe contamination