emissions fail

I bought a 94 FZJ80 in December and I've taken and failed 3 emissions tests in Colorado due to high NOx. I think I've narrowed it down to a faulty VSV, but I would appreciate some input before I spend the $$$. I've attached the charts from the 3 tests. I took my truck in to test in mid-morning...

Hello Folks, Need your help. My 93 1FZ failed emissions again today with too high NOx levels. Prior to this I’ve replaced the O2 sensors, plugs, wires, cap and rotor. Cleaned the throttle body, replaced the fuel filter, air filter, PCV valve. I’ve been running premium since the last fail a...