1996 Subaru Outback Idle problem

What would make the 'idle air control valve' go out when the car acted up & would not start? Put a new fuel pump & filter and the car started and idled good for a minute and then died and has since died when started.
Would it be because an after market fuel pump was put on it? Which was gotten at O'reillys.
Please respond and let me know. I am over a thousand miles from home (working away from home right now) and this is my only transportation & I can't find anyone that knows anything about Subarus. The nearest dealership is 200 miles away.
The gentleman that always worked on my cars and I have 2 Subaru's past away last December of bone cancer, I sure do miss him.
Please help me out if you can. Coming home tonight I just get scared when it dies afraid that it won't start.

Ok. I just got your reply this morning & after reading my last message I think I meant to say one thing & it came across as another. So, here I go.
My car had been running fine, came home from a trip & the next morning I got into my car to go somewhere & it wouldn't turn over; it tried, but it wouldn't. Took the breather off, put some gasoline on a rag placing it over the exhaust manifold & cranked it up. It started but wouldn't keep an idle. Then, replaced the fuel filter & fuel pump. Now it will start but it won't keep an idle on its own. I have to keep 1 foot on the brake while in neutral & 1 foot on the gas excelerating so that it stays running while I quickly move it into either R or D so that I can go. When I am driving along, as long as I am excelerating it drives just fine & does not die. As soon as I come to a stop it looses all pressure (the rpm's go fastly down) & then dies. I then have to re-start in the manner mentioned above & go on. I will go to the parts store & borrow the gages that I need to run the tests that you sent me a video to & I will get back w/you on the results. Keep in mind, I am a woman by myself & although I do think that I am a little mechanically inclined I do appreciate the visual so that I am able to do this & it may take me a little bit to perform the test because I will have to find someone to crank it so it can be tested (I will ask @ the parts store).
In regards to the video & the 'fuel injection pressure test'; it will not start & stay @ an idle so I am not sure if keeping the excelerator going is going to test it right or not.
Again, thank you for all of your help. It is very much appreciated and God Bless you for that. Your Mom should be very proud of you!