I have an 87 z28 with a 305 tpi, when driving it the other day the passenger side door was partly open so i opened it and slammed it shortly after the car stalled, idk if this is relative to the problem. It then started sputtering almost as if it wasnt getting fuel or air, it started getting worse at high speeds it would stay constant but when coming to a stop it would sputter and stall, its gotten worse now the idle fluctuates and then turns off, starts fine but then problem persists, changed fuel filter and fuel pump and no luck anyone encountered this problem before??? if so or any feedback please help???

 

Is the check engine light on? Check your fuel pressure. When was the last time you did a tune up? Plugs wires cap rotor?

 

I would replace the IAC (idle air control) valve and see if that helps. If it has never been changed it will cause idle problems due to sticking and not moveing free. It is a low cost replacement part in the $35 range.