95 tracker miss after warm up

[fixkick]

150 was cold on all cylinders
ect reads 300
tps all smooth
o2 seems to make no difference plugged in or not no cracks in exhaust
need to pull ecu to check
fuel pressure was taken at the cap at the end of the rail.
cleaned maf
injectors only make the chattering sound when missing
plugs where fully light gray with no heat lines on the strap.
vacuum was stable at 19 at fpr port

on these years it is very hard to see if the ECU can hold closed loop 02 status.
but  your 1 symptom  above  seem to hint that is dead. (no difference)
try new 02 yet?
in shop we scope the 02 fan see it fail, stuck and not swinging, telling me, closed loop is dead.
we create vacuum leak to see if the O2 wakes up, or force rich by playing with vacuum port on FPR.
that trick on FPR is simple pull the vacuum line and put golf TEE in the sucking hole. hose.
now FPR is 6psi fuel pressure higher and it goes rich, and 02 may wake up. and swing,
if 02 is dead under all tests, the O2 is bad, or cracks near by are there . even exhaust header collector end gasket bad or just loose.
seem this is lean misfire, to me,, most these cars fail rich, super rich and spark tips black.
is the MAF marked 58B00 (and mitsubish logo, like it was new)  the last poster here had this china crap MAF< that had way too high readings, (gm/s)
and no o2 in the world could correct that nasty error.
I see  like 25 china brands sold at amazon, for $20 and all are junk and that means get landed on lots of cars just because  $20 is 1/6 normal price.

I'd see that in person in a minute.  all things wrong just by site,  missing and wrong parts and hacks.
even 02 sensors hacks.
what is your MAF output pin , voltage reading at hot 800rpm idle>>?  spec is 1.7–2.0 volts. at 800 RPM

keyon is 1.0 to 1.6, and idle near 2v.
gun throttle see 3v, and much more driving up a hill making full 95hp on engine.   (a good maf ) if weak MAF 95hp never can happen)  that is why I asked about hills.