Ok so I have a new(to me.) 91 cherokee 4.0l, that wont pass smog.
The first time I went the numbers were
HC@15 max86 meas 76
@25 max 103 meas 56

CO @15 max.73 meas .38
@25 max .93 meas.31

NO @15 max 711 meas 706
@25 max 613 meas 666

So I failed in the NO category. It was hot that day like 90. And I had not done anything to the jeep yet. since i changed the plugs, wires, cap and rotor, did oil change and new o2 sensor. The plugs were gaped at 50 so the new ones were gaped at the factory rec 35.
Today I took it back, I drove the jeep for about 30min before I took it in, I was the only one there so it went straight into the shop.(very little time to cool off.) And its in the high 60s today so its colder out.

This time around it failed again but with higher NO levels.
the other levels only went down a few points.

NO @15 max711 meas 780
@25 max 613 meas 781
So my NO levels went way up.

Any ideas?
I have not replaced the MAP or IAT sensor yet.
Oh the PO said he put a CAT on it in 09. You can tell its newer.