well not a 3800 but it has the 3.1
My friend has a Lumina 3.1 Euro that when started will almost immediatly die or will die as soon as you give it gas. The Fuel pump was just replaced so I thought it might be the FPR.
When I pulled the vac line a large amount of gas came out which makes me think this whole problem is FPR
Might want to ask on the w-body.com forum or the 60degreev6.com forum.
If you suspect a fuel problem plug a fuel pressure gauge into the rail. On the end of the rail there should be what looks like a valve stem cap. Take that off and there is a schrader valve to put a fuel pressure gauge on. It should have over 40psi fuel pressure.
I would replace the FPR. I bet that will fix the problem. When you give it gas it just sucks more fuel from the FPR and causes the engine to die. If it was the tq converter it would die as soon as it'* put in to gear.