fxk4

Hi all,

I have a 1999 5.0L V8 Mountaineer.

Recently, it started hesitating on me during startup and while idling, and the check engine light has been on some time as well. It usually stalls 4 or 5 times before I get going. Most of the time it is OK once it gets warmed up, but on bad days, it even stalls at traffic lights. A friend from work suggested that it was an easily replacable O2 sensor, but I read that there were 4 of them, so I went to Advance Auto Parts, and they ran the codes to let me know. The printout stated the following:

DTC P1507
Idle Air Control
Underspeed Error

DTC P0401
EGR Flow
Insufficient

Here are my questions:

1) Given the codes and symptoms is there any liklihood that one of them (IAC or EGR valve) is bad and is causiing both symptoms?

2) The good people at the store told me to clean them first, and try to determine if 1 or both is just dirty, which of the components should I try first?

3) Where are they located? I think the IAC is right inside the hood on the left mounted on some sort of ventilation duct, and I think the EGR is underneath somewhere in the exhaust system, but I need a little guidance to locate both for sure.

Thanks a lot for any help!!!