Engine stalls

I have a 2003 Malibu where occasionally the car stalls on low fuel pressure when coming to an idle. I have changed the fuel pump, fuel filter, and the mass air flow sensor. The car ran fine until I came to a stop and it died. Tried to start it several time, but it wouldn't stay running. The next morning it took four times before it started-drove it to the mechanic shop where it almost died twice at a red light and upon arrival at the shop it idled fine but when I press on the accelerator it would rev up to 3800 rpms the drop to 3000rpms then back up to 3800 rpms and repeating this action over and over. One mechanic put a pressure guage on the fuel line where it would hold pressure at the start but after ten seconds or so drop to zero and die, but would start right back up but die again. Then on a another occasion the car sat and idled for an hour and a half. Do you have any suggestions?