Cessna 172SP engine quits shortly after start up

Either by going through the start up check list or by simply choosing a particular airport (in this case O24) but other airports have also caused the same problem, I find that the engine will only run for about 15 seconds and then shut down. I've checked to make sure that I don't have any failures programed in and I've recreated the file and even created new files from scratch but each time I try to start up either on the runway or from GA parking the engine quits. Other aircraft such as the Beech Baron don't seem to be affected but I like the Cessna for what I'm doing right now and I want to solve this problem. This is a relatively new problem that's cropped up. I've been flying the Cessna for a while now and nothing has changed. I'm running FSX Gold with Acceleration and Saitek yoke, throttle and pedals. The simulator doesn't crash the aircraft engine just quits running. So there are no error messages to give you.

Thanks in advance.

System Specifications

Motherboard

Biostar A870 Ver. 6.0

Processor

AMD Phenom II X4 965 3.4GHz

Memory

Patriot DDR3 2000MHz 2GB (2x)

+CL +RCD +RP +RAS

9-11-9-27 1.65v

Sector 5 PGV34G2000ELK

Video Card

NVIDIA EVGA 8400GS 512MB

P/N: 512-P3-1300-LR

HDD

Segate 500GB

P/N HD502HJ

DVD

Samsung SH-222

PSU

APOWER AK Series

850 Watt

Lee Vining is over 2000 meters ASL so you probably need to lean the mixture a bit to keep the engine from flooding.

peace,

the Bean