1997 Ford Mustang engine keeps dieing

Engine Performance problem
1997 Ford Mustang V8 Two Wheel Drive Manual

I have a 97 mustang cobra, when im driving at any speed the car seems like it turns off but only in the sense that the rpms drop and when I push the gas nothing happends, but when I shake the car it comes right back like I have a elec problem. It sometimes does it at idle, I put a fuel pressure gauge on the car and when it is idleing and ahd the problem happens the fuel pressure increases like the fuel is not being deliverd passed the injectors. There is a box in the right front wheel well that I thinkk might be the problem because the past owner ripped out the inner wheel well and this box has be in the weather and has some corosion on it the part number on the box is. F6SF-128577-AA and it has a 101 and a R on it also, please let me know what you guys think and what this box does please. Im stationed in england and have no where to take it to.