84 500 SEC IDLE DROPPED FROM 7 to 2

84 500 SEC hard starting and has trouble running when foot comes off gas pedal, rpm goes under 5 and car shuts down. Problem just started, I thought I had run out of gas at first because car would start but shut off when foot was off gas pedal. So I put in a container of gas and she started right up. I drove home and problem reappeared on next start up. I hear a humming from engine around air filter, I placed my hand on what I believe to be cold start value and feel a hard vibration. I do not know if its the value or fuel pump causing the problem. Can somebody help me? Car will not idle at correct rpm.
One thing different I noticed is when opening gas cap I no longer hear vacuum sound that I usually hear after driving car. Last Test I ran turning ignition key but not starting car, I did not hear fuel pump start. Can anyone give me some pointers on how to narrow down source of problem? I found #11 fuse blown, looks like spark plug wires may have touched idle control unit and shorted it out, that is what i believe is the problem.