I have an 89 2.8. One day it runs fine, the next day it coughs, and sputters, and will barley do 30 mph, the next day it runs fine again. Sometimes it stalls, and won't restart. Sometimes it's hard to start, the next day it starts right up. Also, it's 20 psi low on fuel pressure. It runs about 26-27 with the engine running, then drops to 11 when I turn the key off. I've been told it should have 47psi. I've gone through everything. I've replaced the fuel pump (twice), the filter, the pressure valve, the fuel pump relay, the mass airflow sensor, and the injectors. I am at a complete loss, and need help.
Also, the injectors I put in were reconditioned ones. They measured about 3-4 more ohms than they were supposed to, but they read exactly the same as the old ones, so I put them in. Checking with a stethoscope, they seem to be working just fine.
Help! Help! Help!

 

1st check your voltage @ the Pump harness connector.
are you sure your not leaking at the injectors- twisted O-ring
just because you replaced the Pump. Does not mean anything.
I have witnessed out of the box FP's fail. Or fail in 1 week. If your Fuel pressure is not above 38 PSI from the initial prime. you have a weak FP OR FP regulator leak, Inj O-rings leak.

 

I'm getting full voltage, no twisted O-rings, replaced the fuel pump twice, besides some days it runs just fine. New pressure regulator

 

2 options. Debris build up and Clogged. Weak pump.

 

I've blown out the fuel lines, I've changed the filter for the second time. I'm thinking about changing the pump for the third time.