"car sometimes kills"??? Evil car?
Could be a bad compressor, causing too much drag on the engine. Was this recently converted? If so, take it back to have it looked at.
The idle is supposed to adjust when the A/C kicks in and I believe there maybe a switch on the compressor, but others will have to chime in.
[This message has been edited by jaskispyder (edited 03-18-2015).]