So you bought pp2000 but don't have a laptop to load it onto...?
Relay or lp pump seem the more likely culprits tbh, else it wouldn't be so intermittent - the HP pump isn't likely to be able to make the pressure one minute and not the next. Have you actually checked anything other than the fpr yet? Done injector leak-off tests, had a look a the relay for signs of damage, checked the lp pump etc..? That's how diagnostics is done when the computers can't cope.
Cleaning the maf won't help, completely unrelated.
Relay or lp pump seem the more likely culprits tbh, else it wouldn't be so intermittent - the HP pump isn't likely to be able to make the pressure one minute and not the next. Have you actually checked anything other than the fpr yet? Done injector leak-off tests, had a look a the relay for signs of damage, checked the lp pump etc..? That's how diagnostics is done when the computers can't cope.
Cleaning the maf won't help, completely unrelated.