2001 Expidition low idle

[LDub]

I have a 2001 Triton XLT that has a problem with the idle. It will idle at 500 RPM's but no higher. It started 3 weeks ago and lasted for 2 days, then the idle came back up to 1000 rpm's and it acted normal. this started again the other day. can anyone help?
also I notice that while idling at 500 if I take the oil cap off it tries to stall???

 

[Bedrck47]

OK Now for a DUMB question Which TRITON engine do you have??

Not really a dumb question because both engines that were in the 2001 Expedition are TRITON engines

 

[LDub]

It's the 5.4

 

[LDub]

I'm thinking the IAC or a vacuum leak but not sure where to look for the leak, I cant hear it but do hear something that sounds like a leak during acceleration.

 

[Bedrck47]

take a can of carb cleaner and spray it around the vacuum hoses if you have a leak you will hear the rpm's increase Pay attention to the hose in the rear of the throttle body

You could also clean out the exhaust port thru the throttle body although that port doesn't clog up as bad as the ports thru the 4.6 TB

Are you getting ant CEL on or have you had the codes read