I keep thinking BATTERY....but just does not seem logical unless the alternator has a weak output or is intermittent at times or the battery is not taking a charge any longer.....

In the three events, first one being the long drive home (45 miles), plenty of time to charge battery, unless...reasons above.
2nd: at end of short drive...about 8 miles...but why not earlier in this trip?
3rd: at start-up, makes sense if battery is low, but then after only running engine in limp home mode for about a min, then shutting off engine, re-starting...battery would be even lower after just starting a min earlier.

Just does not seem logical to me at all.

Think I will go get it load tested tomorrow......

 

I changed-out the TPS, got a replacement Denso one. Carefully took measurements on the old TPS prior to removal so I can get the new one at approximately the same angle and everything.

Did the hard reset...I think....did it twice. Engine started without any issues. Went to high cold start idle, then came down normally. Took it for a very easy drive for a couple of miles, then a bit more on the throttle. Stopped engine, did the TPS portion of the reset again....just for the heck of it. Again started engine with no issues. Drove couple of miles back to home.

Will drive short distances the next few days....see what happens.

 

Fingers crossed!

 

Just a short update: so far so good. Been driving the XK8 around locally, short trips, surface street and highways.....no faults have returned. Will be going on a much longer trip tomorrow, several stops/engine starts....will see what happens.

 

Thought I would update this thread now that it has been five months since I replaced the TPS. Happy to report all is good with the throttle body operation. Replacing the TPS fixed the issue.

 

Well done....

 

Thanks for the update; helps all of us!

 

Thanks Lannyl81. Nice to hear feedback on a job well done.....

Until the next time..... when something else may/will/when/what* (*delete as applicable) breaks