Timing, help please

Hey. I have a 92 lude si. I got a new timing belt put on cuz it was cutting out. Now it's misfiring and idling really weird. Does anybody know whether shops time the engine after putting a new belt on? And could having the timing off make the engine run rich/lean. cuz i think they messed up on putting it on or it's not tight enough. Or it might be some sort of sensor. any input would be great