More Help needed PLEASE...95 Lumina still wont run

[ComfortablyDumb]

Here is what I previously posted....followed by additional things we have tried...
My son has a 95 lumina with a 3.1 engine. He just replaced the engine with one from a Cutlass Calais (sp?) His car ran fine for a few days after engine replacement, then began to act like it was missing and chugging and sputtering and stalling. Finally it died and wouldnt start back. A friend of his said he thought it might be the ignition control module, and he had a wrecked car they could take one off to try. They put the new Ignition control Module on today and the car started but still was missing and sputtering terribly. About 100 yards from the house the car died again and now will not start again.
There is a small amount of gasoline in the oil, which we were told could have run down the pistons if it wasn't firing.
When we take out a spark plug it has gas on it, and when we push that little valve thing on the fuel rail gas squirts out. When you turn the key on you hear he fuel pump kick in
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Since that time we have replaced the fuel injector pressure regulator. What happens now is ..after the car sits a day or 2, it will start, and for the first couple of minutes it runs fine...not missing, or sputtering or anything, but as it warms up it begins missing and sputtering more and more untill it dies. ...Then it will not start back again until it has sat for a day or so. I should also say....WHen we replaced the ignition control module it wasnt new. It was one taken off a wrecked car.
We are just at a loss...any and all ideas or suggestions would be appreciated more than you realize.

[richtazz]

you need to run a compression test on the engine both when cold and warmed up. It sounds to me like the replacement engine has a head gasket or piston ring problem that only shows up once the engine is warmed up and everything has expanded. That's where the gas is getting in the oil. Multiport fuel injected engines are harder to flood, so it would take a lot of cranking to get a measureable amount of fuel in the oil.