I recently replaced my "wonderful" plastic intake manifold on my Bonnie. It now seems as if it won't run right. It starts at about 1500 rpm to warm up, but won't idle down until I tap the accerlerator. Also, when it is warm, I will tap the accelerator and it seems as if there is a "dead" spot or a "lag" in response on my throttle. If I do it slowly, no problem but if I "tap" the accelerator....there'* is lag. I also cleaned the throttle body when I changed the intake.

Check everything for vacuum leak. Check to make sure nothing is pinched or binding up.