Venture 97 engine failure

  My Venture 97 Engine 3.4 VIN:16NDX03E2VD257169 GM Mexico, has an strange problem, when it´s cold works fine, but when warms up,hesitates and die. When I try to start again it sounds like the timing were too advanced, wich it normaly can´t happend because of crank sensor. After a while, starts again and fails after gets hot,etc.

 I'll appreciate any suggestion. Thank's.