Use of but-2-enedinitrile will result in endo stereoselectivity due to secondary orbital overlap.
the Diels-Alder Reaction, Part Ihttp://lennoxtutoring.com/2011/11/23/the-diels-alder-reaction-part-one/
My concern is your use of a Lindlar catalyst. What does hydrogenation with a Lindlar catalyst do to alkynes? What does it do to alkenes?
If you're careful, you can reduce the alkene with 5% Pd/C under hydrogenation conditions. This is more active than a Lindlar catalyst. You can also do the reduction with diimide, which will be specific for the electron rich alkene.
Electron rich things usually reduce before electron poor things in hydrogenation reactions.