I own a 2001 Mustang GT with 33,000 miles on it. For the past 5 or 6 months my car has had some issues with starting. Somedays it wont turn over, and sometimes it starts but dies immediately. Within the last 2 weeks when I start it, it turns and dies. It sounds as if your letting off the clutch and it bogs down (is a manual). If I press the gas when it starts it runs fine till I let off, then it bogs down and dies again. This usually goes away after 2 or 3 starts. Well today it had the same problem but it wouldnt stay running when I let off the gat. I kept the accelerator down and it ran at about 1500 rpm for about 20 secs. and it made a hiss, the rpms shot up to about 2200, I let off the gas and it idled fine at about 750 rpms. When I step on the gas then let off, it slowly drops the 1000 rpm, then acts like its gonna stall, drops under 500rpm then jumps back up to 750. Nothing has been worked on or replaced on the car. I have most engine bolt-ons, and havnt added any parts in over a year. Whats going on??? Any ideas or suggestions will be greatly appreciated!!