In my opinion, there's nothing here that indicates nor rules out the fuel pump as suspect and, it being one of the primary components to supply fuel to the engine, it should be at least pressure tested to verify proper pressure is reaching the injectors.

There's a few things that will cause sputtering and in order to rule / factor things out, you've got to do some testing. Never assume because you can hear it - it must be working ok. I have had an Autozone pump that sounded like it was working only to find after popping the hood that the pressure was 35 psi vs 49 psi thus, the sputtering.

Test it. Get the facts.

Next, a bad MAP sensor will also cause the same thing to occur however, 'usually', this will trip an OBD code.

The IAC motor would only affect idle primarily vs. when the throttle plate is partially open thus allowing air into the intake.

Even with a gross leak at the intake, such as a leaky injector o-ring or, worse, pulling off the power brake booster, it will not induce sputtering. This is the intake side.

However, if the output side / exhaust were to be restricted, this would have a huge affect on the amount of airflow coming into the motor thus, if the amount of air/fuel mixture in the combustion chamber is not able to exit, no displacement is going to take place- no output means no input. This will also create a sputtering problem and, it will induce stalling if it's totally plugged at the CAT.

I would start at the fuel supply system first. Verify pressure and rule that out. You may find low to no pressure and, if so, most likely root cause is a spent fuel pump regulator or, clogged inlet at the pump or, low-voltage condition at the fuel pump wiring harness or, somewhere along the feed to the fuel pump motor such as the FUEL PUMP RELAY, MAIN CONNECTOR (under firewall on drivers side) etc etc.

Start there and report back as to what the pressure is. You can do this by placing a fuel safe pressure gauge on what is called the Schrader Valve and running the following tests:

METHOD ONE: NON-OPERATIONAL TEST

- after placing the gauge on the port,

-Turn the KEY <ON> one time

-Note reading.

NOTE: SPEC IS: 49 ± 5 psi. Spec also says it should be able to hold at a MIN, 30 PSI for FIVE MINUTES. If it fails to hold pressure, there's a problem with either the relief rollover valve at the pump or, there is/are leaky injector/s or, there's a gross leak.

-If it's below this amount, repeat test and note reading.

-<IF> psi reading is now correct, the pump is marginal. It works but, is weak.

-<IF> it takes more than two tries to reach full operating pressure- the pump should be replaced as it's on it's way out.

METHOD TWO: OPERATIONAL TEST

With the vehicle running, note pressure. SPEC is same as described above. If the needle is bobbing / bouncing, there's a leaky injector or, gross leak that needs to be addressed and, if and when that occurs, let me know and I can help you find the leaky injector without removing it.

Start there. In no way am I saying that the root cause IS pump related but, I would like you to at the very least test it and rule / factor it out as suspect. Once that's done, you can then move on to the next phase of troubleshooting.

Regards,

CM