Do you have a torch?.. if not get one, preferably with map gas, you can use the same style igniter that fits on the propane cans, I think sometimes its call propylene instead of map, but should be a yellow can.
At the same time, I see you have the 1.8l motor, I'm not sure how this affects the 96+ with obd2, but mines obd1 with a single o2 in the exhaust and I banged it on something when putting in my manifold and it is dead, and to be honest the only thing it is affecting is my gas mileage and air/fuel guage. Otherwise runs fine. If your cars running that bad it could be something else on top of it.
Another thing that helps is an impact gun, I used one of those shitty electric ones when I had my regular bp exhaust mani, it fit fine after removing the fan, but lots of heat is key.
btw.. If you havnt used a torch before, you dont need a fancy one, just goto your local hardware store, like home depot or somthing.