hesitation and random misfire (4.3L Vortec 95 Jimmy 4x4)

Good day,

If there are any GM techs here, perhaps you could tell me if I might be
missing something. I can¹t seem to shake a +25% Long Term Fuel Trim issue
that causes hesitation at low rpms and occasional random misfire and cyl 1
misfire codes. The fuel pressure at the rail with the key off is 58psi and
52 constant while running. Engine vac is steady between 18-19in Hg and a
propane test on all intake/plenum gaskets, etc shows no leaks. I have
checked and verfiied the IAC and EGR. Both O2 sensors have been replaced,
the TPS and MAP were replaced replaced (TPS had a flat spot and the MAP
pigtail needed replacement anyway). The plugs (all regapped to OE specs)
were all replaced, new cap, rotor, coil and wires. There¹s no arcing when
I kill the shop lights. I had an issue awhile back with a leaking fuel
pressure regulator and slow/no starts. This was remedied with a replacement
FPR. I am considering that there may be a stuck poppet injector that¹s
leaking fuel into the cylinder causing the misfire but this theory isn¹t
supported by my fuel pressure readings. The in-tank pump and screen have
also been replaced within the last few months. Other than trying OEM wires,
perhaps replacing the ignition control module or worst case, needing a new
fuel spider, does anyone have any other ideas of what I might be missing? A
Œtap test¹ of the ECU shows no change in fuel trim/hesitation. Water
sprayed at the cap,wires shows no arc or stumble. The distributor is new as
of maybe 6mo ago and the current problem didn¹t exist at that time so I
don¹t think it¹s a bad gear.

I¹m off to get a motorvac treatment at a local shop today in case one of the
poppet springs is a gummed up or something.

Thanks and take care,
Andrew.