Warm hot idle issue mixture control ?

[36brua]

Hi all
89 I stk except for Mark D chip. all maint is current.

idle started to fluctuate 750 - 500 +- up/ down blip throttle engine will clear and idles ok then cycles again. does not die and will take gas. idles fine when cold. drives ok when warm/hot.

I had a quick diagnostic test run ,came up with #10 mixture control.
I have not run the Bentley suite for warm/hot idle prob. yet will do this evening, I'll chk clean ICV and AFM, leaks, coolant temp sensor etc. I have a new spare'white' coolant sensor ,vs blue as noted for 325 I, Bentley shows diff resistance on testing can this be used in the B25?
any thing to add to list ?
of course I'm suppose to drive to So Calif tomorrow ha !
thanks

[nando]

no, don't use the wrong sensor. the ECU is pre-programed with a resistance curve for the blue sensor, if you put a different one in it will mess it up, badly.

[36brua]

no, don't use the wrong sensor. the ECU is pre-programed with a resistance curve for the blue sensor, if you put a different one in it will mess it up, badly.

Thnx for the confirmation