I have an 84 12a completely stock Rx. Did a search of the archives but couldn't find an answer to this particular problem.
The car always idled perfectly at 750. Then a few days ago it would not idle at all, would drop to zero and die. Changed plugs and fuel filter, solved the problem for two days then it came back even worse. When cold, and choke pulled out it will idle at 2000 rpm, then surge up to 3000, then down to 1500, then back up to 2000. When warm it will not idle and is now how to start when warm (it never did this before) I NEED this car as my daily driver so any help or a point in the right direction would be greatly appreciated.

 

I suggest check for bad coils which usually malfunction when hot.