Subaru Brat 1983 skips and surges

[FriendOfBrat]

My roommate owns a 1983 Subaru Brat. It has this problem in which it goes up a grade, it'll surge and stop, surge and stop, until the motor dies. My roommate has replaced the oxygen sensor, something that starts with an E, the fuel pump, the gas tubes, the vacuum something, and some other stuff but the problem is still occuring. What can anybody do? If you need more details, let me know.

 

I just spoke with him. He has done the following: All vacuum lines checked, replaced vacuum sensor, the EGR valve, and the fuel sensor, no problem with piston or rings, what else is there check?