phenylalanine isn't a precursor to PEA, it's a precursor to dopamine (but not a direct one, it is subject to the rate limiting step - L-dopa is the direct precursor which is not subject to the rate limiting step, however even that is not like taking a dopamine releaser or reuptake inhibitor). Inhibiting phenylalanine breakdown won't do anything, as it is an amino acid that your body gradually uses to produce dopamine.
An MAOI will inhibit the breakdown of PEA, but it's potentially dangerous and shouldn't be done without paying close attention to dosage.
You're not gonna get enough PEA to get high from chocolate. If you get pure PEA powder, you can get high if you eat over a gram of it, but the high, though surprisingly pleasant, lasts 10 minutes and then it's over.