I'm not a mechanic but seems like a fuel problem issue. If it fires and runs out of gas when you dump into TB.
If regulator works it could still not have enough fuel to regulate. Fuel filters clogged? Injectors clogged? Pump bad?
I'd pull off fuel hoses and check they're getting squirted in a 2 liter. Or use some kind pressure gauge I don't have.
Careful of fires. Not the safest way.
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