Honda: 1993 honda accord, honda accord ex, first 30 minutes

Question
I have a 1993 Honda Accord EX automatic, it starts hard each morning, turns over good but just does not want to start very good. After you do get it started and it warms up it runs great and drives great and will start good until it sets overnite and then hard to start again. I replaced the main rely thinking this may be the problem but it did not help. The engine light is always on along with the D4 light flashing. Has been this way for a year. I had it to two mechanics and they cannot figure out. I am thinking a temp. sensor not working proper but I replaced a couple already and they did not do anything for the cause. If you have any suggestions I would appreciate it.
Thanks.  

Answer
I'd start with pulling the code that is stored in the computers.

Check the fuel pressure with a gauge and verify the car has proper fuel pressure during the initial cranking. If the pressure is good, pinch the return line and turn the engine off. If the fuel injectors are leaking down the fuel pressure will drop significantly in the first 30 minutes after the car is turned off.