My car rpm drops at 500 or 400 and almost stalls

[Ferdi]

The rpm drops at 500 or 400 and almost stalls. It usually happens when the car is Idle at at traffic light stop during very hot days. It happened twice this week.
Can anybody help.
I have a VT 1999.

thanks

 

[gungazza]

is it a v8 check ignition module