Help?

I wasnt sure if this was the right forum to put this in or not but, My xj has been running rich and it backfires once in a while and it seems like it is lagging alot when i get on the throttle, it seems to run ok on the freeway but it is not iddling the best. Anyone have any ideas on what might cause this? I replace the TPS and crank shaft position sensor, i also went through and made sure all the o-rings and what not was good in my injectors.