im actually going to purchase a tach hopefully this weekend. in park it's idling a little higher than i like to hear.....if i had to guess the idle in park is around 1000-1200, when i drop it into drive the RPM's go way down for a moment and then evens out where i would say about 800. my original guess a while back was a vacuum leak where the intake meets the heads but i sprayed around the perimeter with carb cleaner and there was no RPM change