- When you say the coolant temp sensor keeps breaking, do you mean the same sensor has intermittent problems, or you keep replacing the sensor only to have it break each time? The problem may not even be the sensor but the wires and/or plug that go to the sensor. Get an ECU pinout diagram and check for continuity between the temp sensor plug and the corresponding pin on the ECU plug next time the sensor isn't working.
- Use dielectric grease (get it from Repo/Supercheap/Autobahn) where the high tension lead plugs onto the coil. This will help prevent any arcing, also make sure the boot on the high tension lead is not damaged where it plugs onto the coil.
- Try setting your throttle position sensor as per the 4AGE manual. But I'm pretty sure the car will actually drive reasonably well without the TPS, it may stutter a bit on takeoff or something but it shouldn't be too bad.
Also having the cold start injector and idle-up hoses etc blocked off with bolts is pretty common.
Going to a redtop/smallport will be a pretty big task, you will need to modify a smallport manifold (only came in FWD format) and wire up a new loom at the least.