Sentra will not idle

My daughters 2000 Sentra GXE 1.8 liter had the mass air flow sensor go bad last week. I replaced it and it seemed fine. Now, when you start it and the engine is cold it dies. You have to restart it about 5 times. When it warms up a little it stays running, but idles rough. There are no codes in it. I have looked everywhere to see if I knocked a vacuum hose loose but can't see any. Any ideas??? Thanks

make sure the MAF sensor is facing the right way, also did you disconnect the neg battery terminal when installing? if not disconnect it and leave it off for 30 min to an hour, then come back, reattach it, and look up the procedure for the idle relearn. i think chiquae posted it up on here somewhere, if not you can get it at b15sentra.net

there is an arrow on the maf that should be pointing with the airflow, sounds stupid but i messed it up installing my CAI and couldnt figure out why it kept dying

^^^that sounds like it. idk how'd u get that mixed up though since the maf tube connects to the air box only one way so idk. by the way, the idle relearn is actually sticky'd on the top of the sentra forum. its in the title. battery sounds about right as well. did u remember to plug the maf back in? i remember forgetting to do that and the whole thing just dies. check your intake tube from the throttle body for a leak. if there is an opening there, then it will die as well.

i did one of the couplers backwards, wasnt paying attention, but it did bolt up and all that shiz, just backwards

New info. My SES light came on. I had it scanned and had the following codes. PO430 Catalyst Effiiciency Below Threshold ( Bank 2), PO455 EVAP Emission Control System Leak (Large), & P1448 Mfg. Control Auxiliary Emission Controls. Any ideas. Thanks again

tell ya what. check your fluids. running bad oil willo send these to the ecu. check the air filter and spark plugs. if your oil is turning a dark black, change it immedietly. i got a code like that onc4e in my 01 sentra 2.0L. changing the oil and oil filter made it go away and run like new. try that. if that doesnt work, sounds like you need a new exhaust system with catylist.

bank 2 is reffering to the cat right after the header. if your car has under 75k miles, i believe that nissan should change it at no expense for you.