engine quits after throttle snap 2000 Maxima

2000 Maxima dies after the throttle has been snapped open.Vehicle has 220,000 kms and plugs were changed at 120,000 kms.Vehicle has 3.0 ltr engine.I am wondering if the fuel pressure is the culprit?There was a code PO171 which was cleared and has not come back since.There have no other codes appear.Vehicle would start cold but would not get over 2000 rpm.Mass air flow sensor was changed and has cleared up the cold rpm issue.How do you check the fuel pressure?Do you need special adapters to check the pressure?On the fuel rail I did notice two vacuum operated diaphrams.Which one is the pressure regulator?Help to fix this problem would be appreciated.
chuck's

....would start cold but would not get over 2000 rpm. ...
Mass air flow sensor was changed ...

2k rpm: 'Safe Mode' ceiling. Typically activates when MAF or rpm -signal missing... Also can be bad tranny rpm/temp sensors.

'New' MAF possibly semi-dead, try another.

1st Check Charge Voltage at batt AND at computer, std 14.2V.

Run self diagnostics, test TPS.

Fuel hose stiffens when pressure is up. Nonissue here.

Platinum plugs last 100k, std 5k. Do change.