Sometimes, when i start (cold or hot, it doesn't matter) my 1996 xjr x300, the engine runs rough on normal idle speed and doesn't perform, and after 1 minute driving, the problem is gone(than it run's smooth).
what can be the problem?

 

Clean the injectors, the fuel filter and double check the trottle body. I'm not saying this is the problem but this is the cheapest way to start.

 

Hello, the injectors are recently cleaned, new fuel filter installed and the throttle body is also cleaned nalso idle air control valve. and the problem isn't solved

 

The only other two options I can recommend; check the pressure in the fuel pump and last but not least go to an auto repair shop and put it on a systems scope. The systems scope will will save you a lot of time and maybe some money because the scope will direct you straight to the problem. If you decide to go with system scope make sure you go to a repair shop you trust, because if they are not your friend it could be a $5 problem and they tell you its $500.