Would it be a plugged catalytic converter?
I doubt if the catalytic converter or is the problem, “usually the car will idle perfect, timing is perfect” and when you drop it into gear and give a little throttle the engine will die because the converter is plugged or in the case of my Dakota, the converter was loose in the housing and would rotate enough to plug the exhaust causing a 90% loss of power until it vibrated into another position and allowed the exhaust to flow. A converter will heat to working temperature in a matter of minutes and will glow brilliant red if the exhaust mixture is loaded with hydrocarbons from partially burned fuel, rich mixture or misfiring spark plugs. I would look for a lack of fuel from percolation somewhere in the fuel line, weak fuel pump or possibly a bad sensor (temperature sensor would be the first one I’d check). Check the EGR valve and the PCV valve as well, the idle air controller would be on my list as something to consider too. I believe I would check the fuel pump first for proper outpu
