Now that's interesting. I have the dedicated return wire that is common to all the sensors (wiring diagram here, if you're interested:
http://www.tmproductions.com/s/DeLorean-EFI-Wiring.pdf ). I also added a ground bus that runs from the headlights to the engine block; the grounds for MS is connected to the end of this bus at the engine block (mostly because this is Josh's harness, and that's how it was set up; I made my own diagram because I had to put on the DB37 connector, and I wanted to make sure I did everything correctly).
I haven't had to look into noise issues before, so I'm not entirely sure how to proceed. I'm guessing culprits could be wires that run too close to the coils, maybe? The VR sensor is a shielded cable, but everything else is just simple wires. It's interesting (well, to me) that that MAT and CLT spikes don't seem to be at the same time. Also that TPS is smooth; I'd have expected noise in all of the sensors. Of course, TPS appears to be wildly off anyway.