If you've scanned your Ford Probe's ECU after replacing the EGR vacuum lines and the intake Air Temperature (IAT) sensor, and no trouble codes appear, we can recommend you go ahead with the smog check to find out the new results of the test; hopefully they will be passing.
Having repaired the EGR vacuum lines more than likely got the EGR valve working again, and subsequently lowered (will lower) NOx emissions during the smog test, and thereafter.
As far as the Fuel Pressure Regulator Solenoid, should you need to replace this part, and you might not need to since it seems there is no longer a trouble code appearing for it, is located right next to the throttle position sensor (TPS). The TPS is attached to the intake manifold exactly where the intake air unit's duct is attached to the intake manifold pentium. The FPRS should have a black cap on one end and two vacuum hoses attached; one on its side and one on its bottom. This solenoid is crucial to the proper operation of the fuel pressure regulator, and the fuel pressure regulator is crucial to proper are/fuel mixture.
If after the next smog test your Ford Probe still fails the smog test for high NOx, we'd recommend checking fuel pressure, the fuel pressure valve itself, and the fuel pressure valve solenoid for proper operation.
