I've built a few hot rod harnesses to help sort out issues folks were having. Sensor leads can be a challenge. For your TPS spike issue, you can do a couple of things. I don't know how many wires are used but you can twist pairs of them together and twist multiple pairs together. Shielding should help as well. Generally the shielding is only grounded at the ECU and not at the sensors themselves. This minimizes the noise picked up on the sensor lead. Do not run these wires parallel to other wires and when crossing any high current wires, cross once at a right angle. Hope this helps.