I just replaced the TPS on my 96 today and had the same "problem". I thought it was suppose to go on straight but I had to twist it a little bit to get the bolts to line back up. It is idling low and where I want it to be, but there will always be a little strain on the teeth the way it is now so I'm unsure if that is correct. Is this normal?

 

According to 2000 XJ's FSM that's how it's designed.

 

2000 XJ Auto 4.0 - Broke my TPS while disassembling for a cylinder head job (was successful, Clearwater) and I tried to put it back on the way it looked like it popped off. I'm going to "adjust" it tomorrow morning using trial and error...I'm assuming I'll just have to twist the teeth one quarter turn to the air intake valve turns and grabs it sooner. The issue manifested as a shifting issue, after the head job it started shifting only up around 3000rpm and didn't know what the heck it wanted to do when it came to downshifting. Only put 2 miles on it since head job.

 

Yes, it's normal to engage it then have to turn it slightly, preloading it as it were. I don't think it's possible to install the HO TPS incorrectly without causing it to hold the throttle open. There is no adjustment on the HO engines, unlike the older renx non-ho engines which had slotted holes so you could adjust the voltage at idle.

Check that the throttle body to trans cable is properly adjusted after you likely had it off during the head replacement.

 

Took about 10 mins to fix, had to align the spring and pre-load it as I put it back on. This XJ is now driving like new fingers crossed.