Help ignition..here we go again,,,

Yesterday I spent 3 hours putting in another switch..today I went to harbor freight and the motor kkkkked all the way there ..you know pinged but only while giving it gas..cruising was ok...when I got out of HF it would crank but not fire..till I realized it wanted to fire if I cranked then let go of the switch..then it would catch..the old switch did it on occasion also..maybe the run wire [brown maybe]isn't getting power???till I let go of the switch in crank position...still having a light pulse bright ...dim...on the headlights..another switch didn't help that...also put in new tumbler..keyswitch...halppppppp,please...j