Coolant temperature sensor location

We have a 2002 Jaguar model-S it has around 130000 For the longest time we have been having a problem with cold starting after trying 3-4 times it will start. There is a strong gas ordor coming from the engine compartment but cannot see any leek. We've been advised to depress the accelerator pedel to the floor which seems to help some with the starting. To date we have replaced the fuel pump because of the electrical readings, it didn't solve the problem we have replace spark plugs again no help. We also have had the fuel injectors listened to making sure one is not stuck open. All seem to be making the clicking sound of opening and closing. So any help reguarding this problem would be much appreciated.