check your relay as well...
Do you have enough fuel in it? Warning light on? Sometimes when my '89 Heep is down to the last little bit, I can hear the pressure in the tank and then she spits and dies at half throttle.
Another thought would be the pressure regulator on the fuel rail... there's a test proceedure for it as well, you will need a fuel pressure gauge...
1. Remove fuel tank cap
2. Remove cap from pressure test port on fuel rail. place rags under this spot so you don't leak fuel onto your manifold.
3. Connect fuel pressure test gauge to test valve on fuel rail
4. Remove vacumn line from fuel pressure regulator
5. Start engine, let idle
6. with vacumn line to regulator disconnected, pressure should be around 39 psi
7. connect vacumn to regulator, pressure should be around 31 psi
8. if pressure does not read 8-10 psi higher with vacumn to regulator, check vacumn line for leaks or blockage.
9. if pressure is less than stated in #6 or #7, pinch off the return line and recheck pressure (vice grips work great for this) if it remains lower, check fuel supply hose, fuel filter, and fuel rail inlet for blockage. (8 out of 10 times it's the filter)
10. if pressure is high when return line is pinched off, check fuel return line for kinks or blocks, if none are found, replace the regulator
WITH RETURN LINE PINCHED OFF FUEL PRESSURE CAN BUILD QUICKLY! TURN OFF ENGINE IF YOU NOTICE EXCESSIVE AMOUNTS OF PRESSURE BUILDING! (I like to position the guage so I can see it from the drivers seat, just in case!)
Might also want to do a leak down test if it's not the regulator... could be bleeding past outlet check valve on the fuel pump... let us know if you need the procedure or pressure specs for the leak down test.