I just got my 08 Dakota back from having the leaking steering rack replaced. Now the steering wheel shakes/fights you a little bit when turning the wheel while driving. Any ideas? The mechanic told me he thinks the pump is going bad? It was fine when I took it in for an inspection

Try turning the wheel both ways from lock to lock. That should bleed out any air in the system and then check fluid level. Also check belt tension.

Sounds like air in the system. It should work itself out eventually. Alternatively you can get the front wheels off the ground, remove the power steering reservoir cap and slowly turn the steering wheel lock to lock with the engine off 20 or so times, allow it to sit for an hour, start the engine and allow it to run for 5 or 10 minutes without turning the wheel, shut the engine off and repeat the lock to lock procedure. Sometimes just leaving the cap off overnight will also work.

Sounds like a bad box to me, or maybe it needs adjustment if it is like the early Mopar boxes