1997 Nissan Hardbody has rough idle/surges/stalls

Thank You in advance for any help you can provide.
Vehicle: 1997 Nissan Hardbody 2.4L(KA24E)4 cyl. 5 speed, 211,000 miles. Motor starts fine but the idle is rough and the engine surges about every 15 seconds or so. Not always, but that's what's happening. Checked all vacuum lines, TPS, IACV-AAC(replaced), all solenoid switches, EGR, BPT valve, changed the PCV and connecting hose , checked all fuel lines for blockage(clear), injectors all check out ok, harnesses all have continuity and battery voltage present, checked the fuel pressure at idle and is: 36-38 psi(should be 34 psi), then the engine will surge(rev up) and the fuel pressure will drop to 34-35 psi(where it should be). When I pull the vacuum line off the pressure raises to 43 psi and stays there until I put the line back on then hovers at 36-38 psi then surges and the motor shakes due to the rough idle. Any thoughts?! Thanks Again!!! I have a 2001 NISSAN ALTIMA with 2.4 litre engine. It is surging badly at idle. It is showing code for random/multiple misfire.I have replaced plugs, wires distributor cap, rotor button, air filter, all to no avail. I have checked all vacumn lines that are visible and see no problem with none of them. Engine smooths out and runs well at all speeds above idle. Any help is grestly appreciated. I am out of ideas.