M102 stalls when hot
 

The engine is an M102 16v 190E. I have replaced the OVP to fix a problem with poor idle when cold and high idle when hot.

Now, the opposite is happening. Idle is fine when cold but when the engine is hot in traffic (100 degrees or more) it stalls rather annoyingly. The idle just settles a little bit too low and it stumbles and stalls.

Throttle body switches and deceleration shutoff switch have tested OK.

Ideas?

Thanks