You could have a fuel delivery problem. I would recommend to start by checking fuel pressure. Fuel injected cars are very fuel pressure sensitive. Fuel pressure is very important and must be within specifications! But if the pressure is low, it does not mean the pump is bad. A plugged fuel filter, a pinched line, and low voltage at the pump can contribute to low fuel pressure. All three must be check before replacing the pump! You can get a fuel pressure gage at a local auto parts store for cheap.
Fuel pressure testing is frequently overlooked but it is one of the common causes of poor performance. The test procedure must include testing that will insure normal fuel pressure under all operating conditions.
1. Fuel demands are low at idle.
2. Wide open throttle at high engine revs uses the most fuel.
3. Fuel pressure must be reduced when manifold vacuum is high. Vacuum pulls fuel out of the injector causing it to deliver too much fuel if the pressure remains high. Manifold vacuum is used to open the pressure regulator at a lower pressure when vacuum is high.
A good way to check your fuel pump
is to run an amp test on the fuel pump while it is running or while battery voltage is being applied ot it (turning the key on, cranking your vehicle or even when your engine is running. The amount of amps your fuel pump will pull will depend on how much fuel pressure your fuel pump should supply to your fuel rail. A good rule of rule of thumb for this test is as follows:
14 to 15 psi 3 to 4 amps
30 to 45 psi 4 to 7 amps
45 to 50 psi 7 to 8 amps
50 to 70 psi 8 to 12 amps