2000 xlt idles high

[Billbent33]

2000 xlt idle is high - V8 engine- 5.0 Liter-

Hi all
Trying not to beat a horse that is obviously dead.......nonetheless...
2000 XLT with V8 5.0 L engine and 2 wheel drive.
My 5.0 engine has consistently idled high ( 1200 to 1500 Revs) since replacing stock air filter with K& N. Having read previous suggestions I:
1. cleaned the throttle body with TB cleaner to reduce sticking
2. replaced IAC valve
3. Checked for vacuum leaks
4. disconnected battery for about an hour.
5. went to autozone and checked codes..( throws a P-1506 which shows up as Idle speed control). Was advised that 2000 explorers and some earlier years do not have ISC and correcting problem was done by replacing IAC instead.
6. Engine temp is within normal limits
7. Throttle adjusting screw is backed down enough so it does not even touch the spring loaded plate on the Throttle connection

Now....I'm stuck like a carboned up TB but TB cleaner wont unstick me..
Unplugging the 2 wire lead to new IAC valve does not change rpms ( should it? is new one bad?)
Should I take off IAC and tape over the holes to prevent any air flow into TB and see if that makes a difference?
Have not cleaned MAF but will do it today
Is there an ISC module on the 2000 xlt or only the TPS?
Any other suggestions?

Thanks for your help
Bill ( Red Eye)

PS Since initial post I have cleaned MAF, double checked for vacuum leaks and recleaned the IAC module...
Tapping the throttle stop tab and forcing it down to contact the idle adjustment screw reduces idle to tolerable limits ( about 800 revs) but causes accelerator to stick. Tapping the accelerator to unstick it frees up the Throttle Body sticking problem but won't let the idle return to the 800 RPM range....? Time for a new TB ???or can I take the old one apart and clean up the butterfly valve shaft and bushings if there are any??? Or can I replace the throttle shaft or butterfly valve or external return spring or???
I'm stumped.

Thanks again,
Bill

 

[exploded99]

Actually sounds like the throttle cable is suspect. Check it by hand and make sure it moves smoothly - sounds like it is sticking near the end of its travel. Also check in the truck under the dash and make sure nothing is wrong at that end.

The cruise cable could also cause the problem, you will need to check it as well.

Once you have removed the throttle / cruise cables from the throttle body, open it a little ways by hand, and see if it snaps fully shut when you let go of the arm. Move it by hand and see if it feels rough. - if it does not snap cleanly shut or feels rough, the problem is there, and I would remove the TPS and try it again to see if the TPS is causing the hangup ( not likely).

So, accelerator cable, cruise control cable, throttle body, or just maybe TPS. Find the one that is sticking, you should be home free.

IAC should control the idle speed, so it does sound like a hangup in the mechanicals.