Try this. Connect the positive lead of your meter to the brown with white wire at the TPS harness. Connect the negative lead to your negative battery post. How many ohms of resistance do you have?
If this sensor ground reads over 1 ohm that could be your problem. The same ground is used for TPS, IAT, CTS, and MAP. So even though your sensors test good, the ECU isn't seeing the correct signals from them. I just fixed 2 Jeeps recently with this problem.
Note that the ohms test is done with power off, engine off.
Also check for a vacuum leak on the vacuum line going to the MAP sensor.
Try disconnecting the O2 sensor, the TPS sensor, one at a time, to see if the problem changes, then reconnect each one. Also try disconnecting and plugging the EGR vacuum line and see if the problem changes, then reconnect it.
You may have an engine problem, sticking rings, a rare alignment of the gap in the rings, worn valve seals, valves not seating at higher rpms, so I would check compression.
Renix ECU's are rarely the problem.
What RPM are they running the test at????? Mine here are only at about 1650 RPM!!!! Why 4-5,000 RPM????
Check the wires to the O2 sensor, one should be larger than the other 2 and should have about 13-14 volts on it, that goes to the O2 sensor's internal heater. If the heater in the O2 sensor is bad or the 13-14 volts is missing the engine will run too rich causing black smoke (should read about 8 ohms to the O2 sensor ground wire, which is one of the other 2 wires on the O2 sensor, with the O2 sensor disconnected). Bad O2 sensor or bad O2 sensor wires, or bad O2 sensor heater relay will make it run rich and cause black smoke at high RPMs!!!!
Once you fix the problem, run some Gumout through it to clean out the excess carbon before the next inspection.
