I would fix the problem you are having now then put the stage 1 in.. It is best usualy to not add more things to the equation.. plus now you can bring it to the dealership in a more stock version..
You could install stage one.. and plug/wires.. see what happens.. then if it still is doing it.. take the stage one ECU out and put stock ECU in.. and bring it back to the dealership..
Let us know what they say or what happens..
I put in the plug and wires Tommy sells.. they look good and are a good price..
Adam
www.prototypepower.com