Car problem

I have a 94 acura vigor when I turn my ac or headlights on the motor strains(good alternator and brand new battery) and causes the check engine light to come on and then it won't rev over 3000 rpms and my rpms gauge jumps. The check engine lights says it my crank position sensor code 4, and I replaced it with a new one and still does the same thing, And I checked my plug wires while its running and when I pulled my 3rd spark plug wire out it would arc at the distributor(new wires and I checked them) please help.