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Sub-TPS Clicking

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Hello! I have had a hell of a time with my 1994 LS400 over the last couple of weeks. Mainly, I've had a severe issue with loss of power at high acceleration. If I push on my pedal hard, the engine basically dies until I release the pedal. I have to push very slowly to be able to drive.

Current engine codes:
13 (RPM Signal No. 2),
24 (Intake air temp. sensor signal)
25 (Air-fuel ratio lean malfunction)
31 (Air flow meter signal)
41 (Throttle position sensor signal)
47 (Sub-throttle position sensor signal)
71 (EGR system malfunction)

Current TRAC codes:
26 ( Sub-throttle valve does not move even when the sub-throttle valve is controlled to fully open position by ECU)
45 ( When idle switch is ON, main throttle position sensor signal is 1.5V or higher )
47 ( When idle switch is ON, sub-throttle position sensor signal is 1.45V or higher )
51 ( Problem in engine control system )

I initially suspected the root cause of the issues I was having were either my MAF, or my TPS. I replaced my MAF, which cleared engine codes 24 and 25. I then proceeded to replace my TPS. Once replaced and adjusted as best as I could, code 41 still had not disappeared. I also attempted to replace my sub-TPS, (the TRAC TPS closest to the air intake pipe on the passenger side of the car), but the part I ordered had the wrong connector shape so I wasn't able to continue the work. I reinstalled the old sub-TPS, and now any time my key is turned to ACC or right at car start, there is this very audible clicking noise that can be heard from the throttle body. It only lasts for a few seconds before stopping. This clicking noise was not here before I replaced my sub-TPS, and I have found absolutely zero information online as to how to diagnose this issue and/or fix it. I have unplugged my sub-TPS for the time being. The clicking noise is gone, and also my TRAC light has turned off.

As far as fixing the car goes, I can hear a bit of hissing from the engine. Would vacuum leaks be causing the drastic power loss issues I am having? I am planning on replacing my spark plugs and vacuum hoses by the end of next month. In the meantime the car is able to be driven, but I cannot push on the pedal hard basically.

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