3.2 hunting problem
 

I have had this problem for a while - when the engine is hot it won't idle properly, fluctuating between 500 rpm and up to 2k to the point where it will go below 500 rpm and stop, no problems starting it again. When cold it idles around the 850 mark very smooth. I have been through filters, injectors etc without any luck - any suggestions?

Temperature sensor ?

Try cleaning out the idle stabilizer valve with brake cleaner.

Vacuum leaks are another possibility.

Is the hot idle 800 for 84-86 and 880 for 87-89? Too high hot idle brings on that effect.

I had the problem also a while back. I fixed mine by tightening the 12 bolts or replacing the gaskets on intake runners. I used a foot pound torque wrench from Harbor freight . After everything was finished, idle went right back to 800 at idle. The intake bolts just come loose over time. Some of mine were only fingerbtight when I checked them.

I'd start with making sure all of your vacuum lines are in good shape. Make sure your boots on the intake runners are good and clamps are tight and clean the ICV.

+1, unless it is chipped.

Also as suggested check the OHMs on the CHTS. Cleaning te ICV for extra measure.

+1. I also discovered finger-tight bolts on the intake runners of my '88 when I was replacing fuel hoses. Either the gaskets shrink or the bolts vibrate loose over time. Snug them up first, then check idle per John Walker's recommendation. Cleaning the idle control valve won't hurt either.
Since it's okay when the engine's cold, you probably have a vacuum leak that's being compensated for by a rich-running engine while cold. After the engine warms up & the fuel leans out, the vacuum leak is now more apparent & your idle hunts & stalls. I'd focus on finding your vacuum leak. Do a smoke test if you can't locate it after running down the usual suspects.

Thanks for all your advice, I'll give it a try on the weekend