87' z24i cutting out,no codes

[Ding1]

Howdy all.Got a problem that just started.Set up the story a little here.All new tune up parts,new ignition coil,NGK plugs,8MM DI wires,O2 sensor,timing @10* etc.etc.Checked codes in modes 3 and 5.Mode 3 is 44 (all fine) mode 5 after 20 or so minutes,zero,zip,nada codes,no blinking lights.Truck starts right up,idles fine,run around town,engine starts to die,dies,starts right up,tries to die,dies unless pressing pedal.Does this for a few times then runs fine rest of time.

Done it twice now on different days and cannot re-produce the problem,it's just random.Checked fuel pressure,@36-37 PSI,cleaned air flow meter,throttle body etc.EGR function test,fine,pulled regulator vac line,dry.ALL NEW vacuum lines everywhere.Rechecked all vac lines again,everything where they are supposed to go and are on,injectors working.

Having a WTF moment here.Any ideas would be great as I have NO CODES to go by.Thanks mucho for any ideas or help..D

[Rev_D21]

How's the fuel filter? You might have to drive it while monitoring fuel pressure with a gauge. Throttle position sensor may be causing this too.