Idle not always returning to 1000rpm?

[ATK 158 2 Cars]

Got a quirk with my 205 where sometimes the idle doesn’t settle all the way back to 1000rpm where I set it to. Eg will start the car and once warm the SAD closes and idle settles to a nice steady 1000rpm. I’ll then drive it for a bit and the idle won’t go back down to 1000rpm and goes to around 1400rpm instead. Then randomly it will now and again drop properly back down to 1000rpm!

 

Initial thought was sticky throttle butterfly but have cleaned that out and still the same. 

 

i’ve rotated the TPS fully clockwise so it doesnt click - to rule out the TPS holding the butterfly open? 
 

AFM dizzy coolant sensor fuel pressure regulator etc all newish/in good order. Throttle cable is at correct tension. 
 

Don’t seem to have any vac leaks. 
 

doesn’t hunt on idle and drives really well. 
 

Any ideas of what to check/test next? Or does it sound simply like my throttle body is worn? 

 

[ATK 158 2 Cars]

I should also add -

if I physically push the the throttle body spindle (where the throttle cable attaches to) a little to the right when it happens the rpm always drop correctly to 1000rpm

[petert 639]

The TPS has two micro switches, one for idle and one for WOT. If the idle switch is is broken, the ECU won't know it needs to idle. Check contacts for continuity with a multimeter.

 

Idle contacts are 2-18

WOT contacts are 3-18

[Leslie green 165]

The microswitch of the tps should click with the slightest movement of the throttle body ,it sounds like it needs a little adjustment with the 2 screws on it  to allow it to do that assuming its working ok after the tests above although its quite difficult to access the pins .

After a very long run (200 mile) mine was hunting up and down at idle from 800 to 1000 constantly which is possibly dissy wear I think and sometimes wont go back to idle either although not up too 1400 like yours. I don't think throttle body wear is your issue , pushing the throttle butterfly   closed is just restricting the amount of air going in so naturally the idle will fall.

Edited July 2 by Leslie green