Stalling Sierra

I have stalling problems with my SAFARI 98 - V6.
I was told was Fuel Pump. So I went to test the car, but they didn't find any problem. In fact runs good, but sometimes stalls, even driving for a second, then goes well again. But sometimes happens that turning on cranks but won't start. I go few hours later, it starts very well and runs perfectly. It's van well maintained, filters changed, tests etc.
So if you changed already all these parts, perhaps it could be a failure of ECM engine control computer, somebody told me so. So what I will do, I will test everything, also relays, sensors and then ECM, because I had also false light signals of engine failure for 1 year, and I ingore it. Now it's funny that the stalling became worst, the failure lights are gone. It could be also just a worn out wire that carry currency from relay to injections or to Fuel Pumps. I will see. Let me know if you have some more information about yours

I finally got it fixed, the dealer found a leaking intake manifold gasket, after the computer registered a running lean error.