I have a 2001 Ford F-150 that I am having an idle issue out of. It is a 4.6L V8 4X4 standard transmission. So here is the issue that I can not figure out... For the past few months when I push in the clutch the rpms will shoot up to about 2500 rpm and when I come to a complete stop it will slowly start to idle back down. And then after it idles down and I just sit there for a min it starts to act like it is loping as if it had a mild to extreme cam. The truck has 133,000 miles on it but the block and heads only have around 15,000 miles on them. Meaning that it has everything off the old motor on it. It is throughing a code(actually a few) I went to O'reillys and had them read them, even though they told me that they weren't technically aloud to because they have been sued somemany times over giving customers the wrong advise i guess, acording to the codes I have 3 bad 02 sensors and a bad egr. I talked to a family friend who was a mechanic and he told me that it is very rare for that many 02 sensors to go out like that. Oh, and I am only getting around 8 miles to the gallon... Can't be good. I just have no idea where to go and where to start. Any ideas?

 

Make sure the O2 sensors are even hooked up, if they are clean the EGR, run some seafoam through the brake booster vacuum port, put some in the tank. Reset the computer by disonnecting the negative battery for 15 minutes, then drive and see if that helps. But the sensors could be bad.

 

vacuum leak

 

vacuume leak... check the pcv valve or brake booster...line..if they are good check everywhere esle ..

 

seafoam fixes everything lmao!!!
check for a vacume leak