So it seems every time I take my manifold off, when I restart my car I get A horrendous surging/hesitation accompanied by an error code for the o2 sensor.. disconnecting the exhaust sensor does not help the symptoms. Each time I follow a simple procedure to repair.

1. Disconnect battery.
2. Disconnect maf sensor and air filter.
3. Remove air duct between plenum intake pipe and maf.
4. Disconnect oxygen sensor.
5. Remove and inspect spark plugs (to rule out fuel or injector issues). If no issues found, replace.
6. Remove coil pack cover and plugs and test resistance.(1 kohm on circuit one 10 kohm on the second),(both circuits on mine read 10).
7. Check all vacuum hoses to check that isnt the issue.
8. Remove plugs from tps and check resistance on lower plug through rotation of the throttle. The two terminals closest to the motor should read from 1 kohm to 9 (approx), 9 at full throttle. Then remove the tps and clean the terminals, including the plugs. Remove as much corrosion as possible.
9. Reinstall the tps as per the workshop manual. This involves finding the idle switch point using the continuity of the upper two terminals. Position the tps at The switch point, total continuity should exist at idle position of throttle, as soon as the throttle moves, continuity should immediately ceased. Then tighten the bolts.
10. Reconnect all other sensors that were disconnected and the intake duct, ensuring everything is tight.
11. Reconnect the battery and start the car, after putting the computer into real time diagnostic mode. Run it for 5 mins then turn it off. The. Check mode 3 and if it reads 55 then problem of exhaust sensor code fixed (stutter fixed also!)

This is for a vg30 91 third gen.

The problem usually occurs after I change an injector.

I do not mean this to be a total solution for everyone nor does every step I follow probably have any effect but it works, 3 times I have changed the injectors and 3 times this process has worked. Feel free to pick it apart. I'm almost 100 percent certain that the only parts of this write up that have any effect are the tps service and battery disconnection but this worked for me so what the hell.