Getting desperate now.   
1988 Corvette, 5.7 TPI 
59k miles 
bought with 43k.   
This problem has been there since day one.   
gets bad mileage (22 best ever), doesn't like starting when warm, all the signs of bad injectors.   
Hooked the fuel pressure gauge to it today. 
Idle pressure- 38psi 
1000RPM-35psi 
engine off-44 psi 
5 minutes after engine was shut off-40 psi 
10 minutes after engine was shut off-32psi   
Starts great when cold, but if you drive it somewhere, get out, come back 15 min later it cranks for a while, then when it starts runs very rich. O2 sensor was replaced 200 miles ago.   
Now, the injectors check out fine. 
Plugs and wires have less than 500 miles on them.  O2 sensor has about 200.  EGR/Air intake temp sensor/coolant sensor have about 150.    
Only thing else I can think of is the MAF sensor.     
The engine temp is normally around 220.  Possibly a weak coil?   
Any help or ideas are greatly appreciated.