you got air in the lines....go get a pump from autozone for like $30 bucks and some new brake fluid its really easy to do check out this link
like he said above...engine size has nothing to do with brakes. It wouldn't matter if you had a hemi or not...a HEMI equipped Jeep means you have a jeep with a hemi engine thats all....why would it matter what type of engine you had when it comes to braking?
also... did you buy the jeep from the dealer which told you the brakes are normal? if the answer is yes then clearly they just dont want to bother with fixing it or you talked with someone who is partially retarded either or
anyways you can fix this problem with about $40 bucks and 2 hours of your time