You might need an idle jet smaller than 45. Try a 42. You need an idle jet that is small enough that you can turn out your mixture screw at least one full turn. You also should never need to have your needle on the leanest setting IMO. Put it at the 2nd leanest setting and then start finding the right idle jet. Leave the 90 main in too. You shouldn't need any bigger than that on a metra.