First of all I am getting a Check Engine Code P0171. I talked to a Ford mechanic and was told to replace both O2 sensors. I replaced the O2 Sensors with Bosch 15717 and now after installing them with the Battery disconnected the car is running great until you let it idle for a few minutes and then the RPM flutter and the interior lights are also fluttering. But when driving the car runs great. upon playing around in the attempt to figure out what may be causing the problem I places a finger over the M.A.S. and the idle smoothed out. But if it was the M.A.S. (Mass Air-Flow Sensor) wouldn't it run rough even when running at higher RPMs? I understand also that there is a PCV on the 2005 4cyl, but I have not been able to locate it to be able to replace it or clean it. This Escape has 186K miles on it and just had all 4 plugs replaced and now has new O2 sensors. I really need some assistance, getting this problem resolved by process of elimination is getting expensive.

 

If you want to just check the PCV operation, place a finger over the tube leading from the air intake tube to the cam cover. It is the source for the air fed through the PCV, and should put a slight vacuum on your finger when the engine is running at idle. If it doesn't pull a bit of vacuum, the PCV may be gummed up or the hoses plugged.
The IAC - Idle Air Control - regulates the idle speed. If you put it in D or R, turn on the A/C or twist the steering wheel back and forth a bit at idle, the idle rpm should bump up to compensate for the increased load. When you start from cold, the idle rpm should be increased for a few minutes until the engine warms. If those things don't happen, your IAC may be the cause. They can be cleaned with some success, but not always permanently.
tom