runs rough after starting( too much fuel) on 1991 Chevrolet S10 Blazer

engine is loaded up with fuel, i can bring the rpms up for a few seconds and the engine will run and idle normally, about half of the time,mostly during cold weather, this happens and will not clear up even after several minutes, or driving several miles, i've replaced the temp sensor on the intake(for the fuel)that seemed to help last year, i've replaced it again -no help this time, engine has been replaced(low mileage rebuilt),trans is rebuilt, new fuel pump, new plugs&wires,etc.
no diagnostic codes stored, recent code came up as faulty speed sensor,nothing any other times.

If your engine is 'loaded up with fuel,' I think you might have leaking injectors. Be sure that you don't have fuel accumulated in the motor oil, it's a fire and explosion hazard. You may need to find a GM specialist.
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