i think most of what you are noticing is all in your head.

i ran my aftermarket ericks tb at .45xxx voltage idle was the same.

i had bogging during acceleration cause of a sticking tb.

you also want there to be 10-12 mm in slack on the tb cable.

make sure you tb cable isn't on too tight.

mine bogging issues where because of the tb, and once they were fixed. i had GREAT throttle response.

the voltage reading as far as i know tell the ecu how muc the throttlbody is open.

that and the map sensor tell the ecu how much air is coming in at what throttle position.