Are you getting an FI indicator lit?
If so, check your fault codes via the service jumper.
Since it lists detected fault codes regardless of time, you may need to clear prior detected faults, and then check if new faults are detected.
A faulty FPR usually results in low pressure due to the regulator diaphragm failing, with fuel leaking past the diaphragm and into the vacuum hoses at the throttle bodies.
This usually causes an overly rich condition and poor idle at the least, and with fuel dripping from seams of exhaust pipes and flooding intakes at most.
Raise your tank, then pull the vacuum hose from the small fitting at the FPR diaphragm. Switch on the key to pressurize the fuel system.
If you see fuel dripping from the diaphragm hose fitting, then the FPR is bad and needs to be replaced.