if it is/was a stiff link, change the LBS if you still have problems. they should not send you out with a bike like that. you can fix a stiff link by flexing the chain sideways at the stiff pin. you will get greasy hands doing this.
could also be shift pins on the big chain ring (at front) picking up the chain and then dropping it back on the same ring. in which case you may have had a cheaper, wider-than-recommended chain fitted by said LBS. or a bent chain ring. or a poory adjusted chainline and/or rear derailleur. or something else. again, change the LBS if you still have problems.
Prevent mechanical malpractice, use a torque wrench.
And if that doesn't fix it, use a bigger torque wrench.
(sorry, pete)