Did you relocate the trac bar up front?
Are you feeling driveline vibes or vibes thru the steering wheel?
You may need 2.5* shims in the rear if it's a YJ to help correct the angle for your drive shaft. Some folks also raise the motor mounts or drop the transfer case an inch to calm some of the vibes.
Check your tires first like AzTJ said... that's the easiest and cheapest and then go from there!