[ngoma]

Was the IP rebuilt from from the ground up also? What is its history?

Can you identify where the rattle is coming from?

What is the ambient temperature in your area?

How long does it take for the car to reach operating temp.?

What kind of cold start mechanism does your car have? The ones I am familiar with (USA) have a thermostatic actuator as part of the cooling system that advances timing and opens the throttle more, when the engine is cold, to aid starting.