vacuum leak

I have a problem with a vacuum leak everytime i shift into gear, when in neutral or park it idles fine. ive looked at my hoses and everything is connected, and i tightened them all. i already changed for a new idle speed sensor. what else am i missing to check? another problem i have is that my transmission shifts hard, only when it is downshifting i get a jerk or the car doesnt move at all until it shifts. i manually shift it and it shifts fine. sorry i couldnt look this up, but its the only time i get to look up information, and i dont get enough time to search. stupid work:banghead:

Hmm..why are you downshifting a automatic ?

i downshift it manually so that i dont get that jerk, when the car downshifts by itself.

ok took the day so that i can work on my car. tightened all the houses again this morning, and went out for a test drive. still has a leak, but check engine light came on. p0505 again? i replaced the iac some time ago, i dont want to spend another $200 so i did a check from what i read on vfaq. to test the ohms on the iac i got from 1-2 32ohms, 2-3 32ohms, 4-5 32ohms, and on 5-6 i got nothing. so i'm guessing the IAC has to be replaced or is there a way to open it and clean it. i'm going back to the shop that did my engine swap to look at the jdm intake manifold and see if i can take that one. still having problems with the tranny though.

I don't see where vacuum would have anything to do with your transmission. Correct me if I'm wrong but DSM trannys are electronically controlled not vacuum right?

its two different problems im trying to find out. i already figured out why my car has a vacuum leek, now i need to figure out why my tranny is messing up