good sumation there. i'll grab a temp sensor next week while in town. Tried the MAP ages ago when the car first started to cause grief, still getting good fuel economy too so doubt its the issue

It won't be your coolant temp sensor........................ It's more likely a dry solder joint at the ecu, main ecu harness or on top of the BBM. cheers.........

I don't think it's the coolant temp sensor either, I'm still saying he should for all it's worth just pulling the coil out and having a look at it for any outside damage and anomaly's with the resistance of the primary and secondary resistance of the coil.

Can you explain in a bit more detail of how it could be a solder joint at the ECU along with this "or on top of the BBM"?

Before you go buying yourself a new Coolant Temp Sensor you should hear me out on this one:

I'm not sure what class in go karts you race in, but I race in Clubman, and in clubman (I'm only explaining this on the off chance your in a class that doesn't require opening up the jet's on the carby to allow more fuel in once the kart is going), we need to push start them lean as not to flood the engine with fuel, as the engine starts to wind up, the engine starts to get hot, so to cool the engine down again, we open the jets up to allow more fuel into the engine to keep it cool.

Same principle goes for a car engine, when you start YOUR car up, the coolant temp sensor will send feedback to the ECU letting it know whether the engine is hot or not, so on a cold morning, as long as the sensor is in working order, the car should start fine because the ECU isn't telling the Fuel Injectors to inject more fuel into the piston chamber to keep the engine cool. If the Coolant Sensor was faulty and was telling the ECU the engine was hot and it was a cold morning, the ECU will be telling the injectors to inject too much fuel for what it needs, a process that will flood the engine with too much fuel.

If the car is prone to getting flooded on a cold morning, the coolant temp sensor is definitely a sensor worth checking, hope that helps.

A dry solder joint at the ecu or a high resistance connector at the large EFI square plug ontop of the BBM can cause intermittent faults. Also check the main harness hasn't rubbed through on the side of the BBM where it is attached with a bolt.