Stuttering problem

Could be a misfire. You should always test before you replace parts. It saves time and money.

Next pull each plug wire one at a time while the engine is running. You should see a noticeable drop in rpm as you remove the plug wire. If you don't, then that cylinder wasn't firing. You'll then have to inspect that plug/wire/coil for the problem.

If all cylinders are good, then go back to fuel system. Check the fuel pressure regulator and for all injectors firing (listen to them with an automotive stethoscope)