94 LS400 limp mode

[Sir Coolant]

I bought a 94 ls400 2 weeks ago. Drove it 2 hours home. Has a check engine light for both knock sensors (can confirm that the wiring has been eaten) Last week it went into a limp mode (FYI everytime I mention a limp mode it’s the same experience, floor it it surges between 1k-2k, slowly give it gas I can rev it to the moon) . I pulled the code and it was a sub throttle position sensor (code 47). I did some research and everyone that had that issue had replaced their 8 caps and it solved it. However I did remove both tps sensors out of curiosity while I was waiting for my caps to come from digi-key. (did get the tps sensors pretty close to where they originally were, I know they need to be precise) After getting my ecu fix it drove like it did when I bought it. Sub tps code went away. The other day I was driving around and I went to give it gas it was back in a limp mode, similar to what I was experiencing before I got my ecu fix. (I was doing around 30) limp it back home. While limping it home I thought I felt the gas pedal fell to the floor but I wasn’t fairly certain because I was using cruise control. Following day I was driving to see if that issue occurred again, drove it 45 minutes doing highway speeds. No problems, on my way back home I was using cruise control and I went to pass a car by hitting the gas and the pedal 100% fell to the floor and went into a limp mode. Pulled over and turn the car on and off and it would rev to limiter at full throttle. Drove home without using cruise control. On my way to work today I was using cruise control again and it did the samething at high way speeds. I had to cycle the key 3 times before it went out of limp mode. Drove it to lunch and had no problems. After work I pulled the codes and it was still the knock sensors and now I have a tps code 41. I’m fairly certain that I need to replace the main tps. I was following a video on YouTube for trouble shooting. I noticed my results were similar to his but when I was back probing the 3rd wire on the tps harness I was getting 3 volts while he was getting 12. My battery was drain while doing the troubleshooting (radiator fans were running and didn’t turn off) . At this point of time I was done with the diagnosing and was packing up to go home. I jumped my car and it was surging at idle but only staying under 1k. Hit the gas and it was back in this limp mode. I decided that since the battery was at the end of its life span that it could possibly cause low voltages to my electrical systems. I limp it to the nearest Walmart and grab a new battery since my was from 2019 and the battery test I did at work said it failed. Swap the battery and it’s still in a limp mode. Pulled the ECU fuse for 20 seconds and put it back in and got no luck with it. Cycle the key at most 10 times and the final time it wouldn’t start unless I hold the gas. Would not stay running. Called my insurance provider for a tow back to my work and it was going to be a 2 hour wait in my area. I just needed a 5 minute tow so I decided to let the car cool off for around 30 minutes. Car started up fine but still in a limp mode. Limp it back to work. Was wondering if anyone had this very specific issue before. I will be replacing the tps and will go from there. Next possible option would to start diving into the fuel pump and troubleshooting that.

[chc0318]

You need to check your fuel pump regulator too.