MitsuStyle - Engine has bad idle

Ok, got my exhaust today and put it on and thought everything would be good. Now the car sometime dies otherwise it goes to like 300 RPM and jumps back up(when driving). When it just sitting at idle it idles at like 1500-2000 RPMs Then every once in awhile it shoots down to like 900 and then back up. When driving the car it seem to studder a bit when i acc. Also the check engine light is on. havent gotten to checkers to get it check yet but im assuming its the random misfire code. There is also oil in the intercooler piping. There are no lines to the intake from the valver cover or anything. Emissions is gone but all sensors still there. Also the turbo is crasked on the right side by the wastegate. When i got it ported it came back like that. Could I have a bad turbo thats why its studders? I thought my problems would be done but they arent. Help me please, I mean im having thoughts of buying a freakin S10 so I dont have to deal with this shit.
Thanks in advance,
Mike