Weird issue, but now gone and yet to return?

[03Dnasty]

First off, I have an 03 Yukon Denali with 118k on the clock. I've only owned it about 6 months now and so far its been great to me. Then randomly earlier this week I went to start it, it started up fine, but then dinged at me and the dash read " REDUCED ENGINE POWER" & "STABILITY CONTROL DISABLED" WTF?! So I turned it back off, then back on and it was still running like shit and wouldn't go over 30mph even with pedal to the floor. I decided to drive up the the quick lube I work at and hooked up the scanner. Threw these codes. P0120 & P2135. I Checked the TB harness wires and two main engine grounds, both seemed fine. After messing around checking those two things for about 10 mins, I started it back up and had no codes and it ran fine... Hasnt acted up for the past 2 days now. Guessing its just a matter of time till it does it again... Any ideas of what else I could check?

 

[SunlitComet]

2003 GMC Truck K 1500 Yukon 4WD V8-5.3L VIN T

Computers and Control Systems: Diagnostic Trouble Code Tests and Associated Procedures
P2135
CIRCUIT DESCRIPTION
The throttle position (TP) sensors 1 and 2 are potentiometer type sensors each with three circuits:
- A 5-volt reference circuit
- A low reference circuit
- A signal circuit
The TP sensors are used to determine the throttle plate angle for various engine management systems. The control module provides each TP sensor a
5-volt reference circuit and a low reference circuit. The TP sensors then provide the control module with signal voltage proportional to throttle plate
movement. Both TP sensor signal voltages are low at closed throttle and increase as the throttle opens. When the control module detects that TP
sensor 1 signal and TP sensor 2 signals disagree or signal voltages are outside the predetermined range, this DTC sets.
CONDITIONS FOR RUNNING THE DTC
- DTCs P1518 or P2108 not set.
- The ignition switch is in the crank or run position.
- The ignition voltage is more than 5.23 volts.
CONDITIONS FOR SETTING THE DTC
- The TP sensor 2 disagrees with the TP sensor 1 by more than 7.5 percent.
- The above condition is present for more than 1 second.
ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze
Frame and/or the Failure Records.
- The control module commands the TAC system to operate in the Reduced Engine Power mode.
OR
- Under certain conditions the control module commands the engine OFF.
- The message center displays Reduced Engine Power.
CONDITIONS FOR CLEARING THE MIL/DTC
- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.
DIAGNOSTIC AIDS
- Inspect the throttle actuator control (TAC) module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs may set
without any circuit or component conditions found during diagnostic testing.
- When the TAC module detects a condition within the TAC system, more than 1 TAC system related DTC may set. This is due to the many
redundant tests run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting
components during testing may set additional DTCs. Remember this if you review the stored information in Capture Info.

---------- Post added at 01:56 AM ---------- Previous post was at 01:54 AM ----------

If it continues a throttle body replacement may be needed. If the sensor pack alone is not replaceable.

---------- Post added at 01:59 AM ---------- Previous post was at 01:56 AM ----------

p0120 may wipe it self out when the first one is taking care of.

---------- Post added at 02:09 AM ---------- Previous post was at 01:59 AM ----------

A proper scan tool can tell you if the agree/disagree status of sensor pack as you slowly by hand open and close the throttle blade by hand. If you get a disagree the it is screwy.

 

[Eschrichtius]

Im having this problem, any further updates with this? I got two CEL codes:
P0120 & P2135 Throttle / Pedal position sensor.
From what I heard I may need to replace the entire TB to fix the sensor issue. Any truth to that firsthand?