View attachment 1714963702 In the route you want to keep as short as possible and the wires together and away from other wiring, especially plug wires. The twisted pair helps insure that they are together. The concept is if there is noise, and the wires are close, like a lamp cord with twist, the noise is canceled, positive one way negative the other, the sum is zero.
You could also have the pickup polarity reversed, causing significant running issues. But you have not told us what happens at higher RPMs. Likely if the tach is jumping the ignition is not correct, and may be doing extra sparks and missing others. It would feel rough in running, a miss.
