Ford Repair: 95 ford windstar engine, inertia switch, fuel injection system

Question
my van was just taken out of the shop on tuesday 12/23/08 where it stalled out on me and wouldn't start.  the shop said they replaced 2 sensors and they had no problems.  today 12/30/08, the same thing happened to me again.  i let it sit for about 1 hour and then it started.  it felt like it was not getting gas at all at first.  the shop told me they checked the fuel pump and it was fine.  could it be the fuel injection system it is a 3.8 liter engine.

Answer
first the fuel injection system involves a whole lot of components including fuel pump/relay/inertia switch/ecm/injectors-all of them can't be the problem-first if the shop you had it at is a good one make arrangements for a ride for a few days and leave it with them to do extensive testing mainly running it and roadtesting it until it acts up with them-then they can zero in on a fault-fuel or spark once they get that far then maybe they can close in on the problem intermittents can be hard to find. good luck.