Fixed the Fuel npump relay and o2 sensor.
Moved the o2 sensor off the header down onto the main pipe.
Idles perfectly now.
The problem: The engine won't rev over 3500RPM. It sputters and hesitates over 3500, but under 3500 it runs flawlessly.

Also: 89 22RE, 33's, SAS, 5 speed.

 

Is your fuel pressure regulator operating properly? No blockages in the fuel line, and the fuel filter is good? What kind of condition is the fuel pump in?

It sounds to me like at higher RPM, the motor is starving for more fuel.

 

i second that. check the entire fuel system. its a long shot but could your throttle body or AFM be getting stuck form getting more than 1/4 of the way open and starving it of air? i wouldnt think so but i guess anythings possible. but check your fuel filter, regulator, pump, and injectors. i got a feeling its fuel starvation related

 

TPS perhaps??.. it's not too tough to check the resistance across it to see if it's faulty at more than 1/4 throttle..

 

Ill have my friend check fuel stuff today. Seems like the fuel pressure is good. Its around 25 psi when the key is on.
Would aftermarket plugs and wires mess with it at all?