NEED HELP

alright so i bought a '95 gt about a month ago(i've owned several stangs over the years see sig.)it has long tube headers on it....i have had a cold running problem(it would hesitate some until it got warm,which would only take about 2 mins.,or by the time i got around the corner)then it would run good,and pull hard..

now i just bought and replaced the o2 sensors...

did the '95's come with 2 or 4 sensors??????the parts store lists 2 before the cats and 2 after...since i have long tubes there were just 2 on my car,and my brothers '94 gt only has two...

so i bought the ones before the cat...the connectors looked the same,and i spliced the wires to lengthen the harness correctly...but now my car runs terrible...it sounds very quiet at idle,but idles kinda rough...it also hesitates,bucks,and jerks while driving...it is driveable,but is waaaay down on power....it hesitates in every gear...it will hesitate,and then it will kick in normally,and i can fell it jerking at speed....

i'm having my bro pull the boxes out of his trash,as i think autozone may have given me the wrong ones...i do need the ones before the cats right????i want to make sure i got the right ones,as this problem started after i changed them..i did try and reset the computer,and it didn't help....anybody have any ideas?????