Still no fire on #1 plug

[JBohannon]

I was not getting fire to my #1 plug. So I bought rotor body, new rotor, and rotor cap. Put them all on and all cylinders fire ok for about 5 miles. Then the only thing I did was lower idle speed a little and soon #1 quit firing. When I say no fire I could not get fire to jump or even a timing light which lights on others will not light. I switched plugs that did not help. Now I realize I do have fire to #1 if increase engine speed. Any ideas.