I am baffled by a cold starting problem. The car is hard to start in the morning but a ok the rest of the day. Here is what has been done so far. The fuel pump has been replaced, the fuel pressure regulator has been replaced, the coolant temperature sensor and thermostat, as well as the idle air control valve has been replaced, I have taken it to three mechanics and they can't figure it out. I have cleaned the MAF sensor but have not replaced it. Where should I look next?

 

have you measured fuel pressure? any puff of black smoke when you do your first cold start? I'd suspect either an intake air leak, the MAF or perhaps a leaky injector which is lowering pressure at the rail.

 

I have not. I will check it and get back to you. Thanks for the reply!