Alright, to save time I've tried searching all posts on idle surging I'd like some clarification and help; I hoping another shade tree expert can shed some light.

I have an 00 f150 that has an 600-900 rpm surge that is intermittent (50% of the time) for about nine months. It developed loss power and rough idle 5 months ago. I had lean 1/2 banks codes come up with rough idle 5mo ago and again 3 mo ago, changed the #2 COP and then the #4 COP. Fixed the rough idle problem and power is restored both times; the SES doesn't come on but the idle surges continues intermittently. Doesn't matter if warm or cold engine; doesn't matter if wheather is warm or cold. At idle it doesn't run rough per se, but is really more annoying and now has become an epic battle of wills, man vs machine, in my household. My wife seems to be keeping score, and I'm honestly losing badly.

Here's what I've done so far. Cleaned the MAF with MAF cleaner and new air filter - no change. Replaced the IAC - no change. Replaced the fuel filter - no change. Inspected and replaced vacuum lines - no change.

In reading past posts it seems there can be a lower manifold leak. How do i check for this is my first question. And next the pcv valve is rattling something fierce; when I pull it and cover it; it doesn't change the surging idle. I've read a lot of conflicting stories on PCV but this seems to be the most reliable check for it that I read, I'm obviously no expert though. I know it is a 3$ fix; I'll try it this weekend along with 02 sensor replacement. I'm also wondering about a faulty TPS can cause my issue. Thanks in advance.

 

One of the first thing to check is for vacuum leaks. Check all hoses, fittings, and gasket interfaces. Methods to use for checking for leaks include: 1) holding a length of fuel hose up to your ear and listen for hissing or 2) Using a portable butane torch with the gas turned on but not ignited. Run the torch by gasket surfaces with the truck running. If a leak is present, the truck idle will surge.

If no leaks are detected, I'd look into the TPS sensor, DPFE sensor (differential pressure sensor), EGR valve, EGR position sensor, EGR vacuum solenoid, and/or MAP sensor. Note that the PCV valve rattling is a good sign. Typical signs of a bad TPS sensor include low idle and stumbling, where the truck engine will die when in drive but with brakes applied. If the TPS sensor was installed wrong, it could cause high idle.

One last thing, stick with Ford parts for the sensors if possible. I've had issues with aftermarket sensors (and having out-of-wack resistances) for what the Ford computer expects.

 

take a look at the EGR