Resistive leads are pretty essential where ecu's are used, as are resistor plugs, wires leading to the ecu can pick up interference, esp the tps, as this is closest to the HT leads.
You can buy shielded overbraid, that you can run any wires through if there is a interference problem, and then earth one end of the braid.
With interference it confuses the ecu and causes all sorts of problems to misfires cutting out etc.
tabetha