I replaced throttle cable which was obviously worn, now have smooth buttery pedal feel except when it sticks, then have high idle, if I stomp on pedal momentarily it sometimes drops the idle & pedal returns to smooth operation, when it sticks it's hard to accelerate smoothly & hard to drive at slow speeds as engine wants to rev, this creates a dangerous driving condition, when the pedal returns to normal all is fine, when it sticks idle is up & hard to regulate throttle, I have lubed butterfly & just checked cable & seems to move freely when detached from TB

 

Without actually looking at everything , all I can do is ask questions to see if you overlooked anything.

Was the problem present before you decided to replace the cable ? What does worn mean regarding the cable? Please explain.

You mentioned you lubed the butterfly, is it free when the cable is off ? Checked the full range of throttle shaft travel ? Is the tension spring on the throttle shaft clean and free to move?
How much do you need to move the cable and casing to connect the inner cable to the throttle shaft lever? If you have to bend it any amount to make the connection, the cable routing is not right. If the outer casing is clamped to tight to secure the casing, it will cause the inner cable to bind and prevent free movement inside the casing.
Let's see what the answers are before going further, you may just see something you overlooked previously..
I don't recall if there was an additional return spring to insure the throttle returns to full idle position, . Some systems have one and some don't.

 

Make sure the bushings in the TB aren’t worn. If they are,, when the throttle is quick released ‘sometimes’ the throttle plate/s will hang/stick in the bore wedging tight. Next time applying throttle the plates ‘snap open’ with a throttle spike. If worn or tight, they can cause the plates to not close all the way and/or rest against the throttle stop screw.. Generally the throttle plate is held just slightly open on its stop, and doesn’t make contact with the Throttle body itself. If you remove the cable, and the concern is still present, good chance it’s the TB itself. Possibly to loose or worn, or too tight on the throttle shaft. If on a high idle (cable removed) event, apply lite pressure on the cable attachment and see if it corrected to normal idle...

 

When I replaced cable the gas pedal was very stiff, when removed I could see it was almost frozen from rust, once replaced throttle was buttery smooth but soon developed erratic sticking which seems to be getting more frequent, when I remove cable from butterfly both seem to move freely, I don't feel restriction in cable with one end still attached to pedal & butterfly seems to be free, I have lubed butterfly both inside & outside,There is no clamp for the cable, it slots into a rectangular fitting in line with throttle shaft lever, if anything cable is long, no problem attaching to lever, but i do note it hard to get into slot that locates cable, I had added a zip tie to make sure it can't slide off but this doesn't inhibit movement at all, I do see issue with detent cable which doesn't seem to slide easily into the casing, it does seem to activate on full open but again this doesn't seem to inhibit movement of butterfly. I suspect butterfly bushings but cannot recreate any binding when cable off, in driving, once it frees up it is remarkably smooth but when it binds it is difficult (dangerous) to drive at low speeds.
I have owned this since new, originally a 5.8 but now a 5.0, swapped 15 years , 189K miles

 

Questions,,,,Questions,,Questions
I don't know for sure if the cables for a 5.8 are any different from a 5.0. If they are , which did you install?

Could the cable anchor at the throttle body be misaligned?
Was the replacement cable assy identical to the one that was removed?

 

Don't like to suggest band aid solutions, but here goes;

Your auto supply store should have a small tube of POWDERED GRAPHITE. If you get this on you it's worse than never seize.

Position the cable with the disconnected end up and dump some powder into the cable casing . Make sure it goes inside the casing.and work the graphite into the casing good.Get a good bit in there. If there is any possible bind left after that ,,,,,,,,,,,replace the cable assy.

 

I’m amost positive old cable & replacement cable same length, it was 1 year ago but I would have checked, I will try graphite but wonder if Idle Control valve could be cause? I get no restriction whatsoever when I push/pull cable when detached from butterfly

 

IAC wouldn't cause a sticky pedal that you mentioned in your initial post.
Like 'spiking' the throttle on a high idle event, then it instantly returns to a spec idle doesn't really follow IAC ops.
If unplugged, is the IAC functioning at idle?
With the cable removed from the TB, if you push the throttle arm back hard against the throttle stop screw, then lightly attempt to move the throttle open, does it stick??