Engine Light!?!

[modernicy]

Hello everyone, I have a 1983 Dodge 400 2.2 carb with an issue. My engine light pops on sometimes at highway speeds (65 mph+); it will flicker, fade in and out, or just stay on. Once the engine light pops on it will usually go off between the speeds of 55-25 but when the car comes to a stop it will flicker and or stay on. The odd thing is that if I cut the car off the light will go out and stay out until I go back up to highway speeds. The car has been maintained well; it has a new: cooling system, alternator, oil pressure switch, fuel pump, O2 sensor, fuel filter, timing belt, plugs, wires, various hoses, air pipe from exhaust manifold to air-pump, gaskets and seals.

I have also noticed this problem and I wonder if they are related; when I start the car it fires up but then begins to lope and die out until I give it gas. It continues to lope until the engine warms. I notice sometimes when I come to a stop if the windows or top is down I smell an exhaust odor (not really rich smelling but not really like a clean burn too lean?) When the previous owner replaced the catalytic converter the air pipe was not connected... I wonder if this could be an issue or if maybe the egr valve is failing?? Any suggestions are welcome.