First of all, g'day and welcome.
I suspect the primary TPS, which is a bit of a known problem, especially if it is the original unit. The original has black insides and is known to fail.The new unit has blue insides. This can easily be checked and reset with TuneECU. TuneECU is free software for a PC and a small charge if you put it on an Android device. You will also need a $20 cable. It is the best and most useful tool you can ever get for your bike.
Also, it will be worth going over all the fuses and electrical connections and checking to make sure that they are clean and well connected. Especially check the low tension cables on the three coils. They may need cleaning and crimping to tighten them up a bit.
It is possible, but quite unlikely, that water got in the petrol tank. If so, you will need to empty the tank and refill it with fresh fuel.
Another failure which can happen on the early bikes is the ignition switch. It overheats from having too much current passing through it and a solder joint fails. This can be re-soldered, but you will have to remove two tamper-proof screws to get to it. You will also need to install an Eastern Beaver bypass kit, or something similar, to ensure that the problem does not return.
Of course, there are also other possibilities, but those are simple things which will get you started on you search.
