Ok.. My car as you know it by now has 150xxx and its a daily driver and im trying to replace everything to basically make it a newish car..

ive got a EGR problem already(getting rid of it.. might have something to do with it)

but when my car downshifts around 40mph it goes down to 500rpm and loses a lot of power.. i was thinking IAC or MAF or TPS..... im gonna replace them all eventually... (next check)

it doesnt really hurt anything but i just want to know why it does it...

plus its 20 degrees outside...