I was hoping someone here could help. I've had my car in the shop for the last three weeks (waiting for parts and diag), and the mechanic cannot find the problem.

Symptoms:

Vehicle hard to start, at all times except up to 15-20 minutes after its driven, and first thing in the morning.

running very rich, spark plugs are black, all of them, black soot on pavement from exhaust pipe.

running rough, it does not matter weather the car is warmed up or not, but it seems to get worse if its hot.

items replaced:
spark plugs, wires, distributor and caps. fuel pressure regulator, EHA valve(was leaking) coolant temperature sensor.

There is no codes in the system, apparently they tried adjusting the fuel pressure (hex key connector on the fuel distributor), this did help the power a bit, but still no luck with the starting problem, and the miss is still there...

Any help would be greatly appreciated.