i have a rough idle on my 96 blazer, and i am not sure what is causeing it. i have just replaced the plugs, plug wires, and distributor cap plus rotor. could you guys help me and list other things that may cause my idling problem.

Check for vacum leaks..
There are a few things that can cause rough idle conditions...vacum leaks, sticking EGR valve (not a common problem on that model), sticking fuel injectors, low cylinder compression

i have a little oil leak, i think its coming from the passager side valve cover, would that cause low compression in one cylinder.

No.

is there any sensors that may be cause some of the problem.

(i cleaned my mass air sensor about 2 months ago with glass cleaner)

Oh i also had my fuel system cleaned 2 month ago

I have another question, does that honey cone thing in front of the air flow sensor do anything??

did you ever get your rough idle fixed and if so what was the problem