Replacing fuel pressure regulator valve

My 300 CE continues to stall after complete stop and then runs fine at higher speeds. Also, I am having trouble starting the car at warm temperatures.

My mechanic said I needed to replace my fuel pressure regulator valve ($400) and also cam shaft sensor ($300). I have spent over $2000 this year at this shop (new belt, belt tensioner and fan bearing).

I was contemplating replacing the fuel pressure regulator with my Dad 's help and saving some money. I was wondering if this would be too difficult for us to tackle? Which manuals I should buy (Chilton's). Also, do I need to replace the cam shaft sensor? I am not sure what this does.

Thanks,

SPP