1987 V8 Blazer 350 5.7

Sounds like the sensor element inside the mass air flow sensor might be dirty. That will insulate if from measuring incoming air accurately so it won't supply the right amount of fuel. Also look for any air leaks in the tube between the mass air flow sensor and the throttle body, and check for leaking vacuum hoses. Any "unmetered" air that gets in won't have the fuel to go with it. You might also try unplugging the generator. If the engine runs better, the generator could be developing excessive voltage spikes. That is a real common problem with the new design they started using in 1987.