Sync sensor, I'm not sure where the ground goes, I seem to remember it ending up at the ignition module ground point, but I may be wrong. The other two end up at the ECU.
A few tips for sorting out your harnesses. Twist ties are your friend. I usually bundle the wires by the source (like the TPS, IAC etc.) and twist tie them together. Then I run that plastic cable sheath with the slit in the side, the way it needs to be ran around the cage. Find a handy spot that is easy to get to and roll the excess wire into small loops and leave it hanging outside the plastic cable sheath. When your finished, cut the excess wire, butt solder the wires together and use shrink tubing, a drop of super glue at the ends of the shrink tubing makes it waterproof and a forever connection. If the wires are too short, buy an assortment of colored electricians tape, butt solder a patch someplace in the middle and mark the wire with the proper colors every 8-10 inches. By the time you get done 2/3 rds of the wires will be unused anyway and what is actually necessary won't be nearly as complicated as you'd think. Once the wires are in the pülastic sheath, tapping the wires back together is unnecessary, you really don't need it. I've never had an issue with a wire inside the plastic sheathing, I just use small cable ties every so often to keep the wires bunched and again on the outside of the plastic sheathing so nothing pops out. A little extra time now may save you a real headache sometime out on the trails trying to troubleshoot a problem.
Crimp connectors aren't really the way to go IMO, solder and shrink tubing is how I do it. It is too easy to get a crimp connector wrong, with the wire too deep and crimping it on the insulation or missing the wire end and having it look good but not making proper contact.
By the time you get done you will likely know the electrical system pretty darned well.