I recently bought a 91 jdm FC3S S5 Turbo II and all was well up till recently I realised that the car starts very hard(takes a while to start) when its cold but once it starts it runs fine. I changed the primary plugs and its doesn't make a difference. What should I check next???????

 

Check for trouble codes: http://www.johnr.com/cpucodes.html.

If the water temp sensor is not functioning correctly (or disconnected), the engine can become difficult to cold start. The ECU defaults to a much lower injector duty cycle than you'd normally get under cold conditions. Some info here: https://www.rx7club.com/2nd-generation-specific-1986-1992-17/looking-car-has-hot-start-problems-499744/