How far do I go before I say goodbye to this XK8?
 

Had the mechanic read the codes:

Results:
P0171 System too lean Bank 1
C10095 Pump motor circuit failure
U1260 SCP (t) circuit failure
U1261 SCP (-) Circuit failure

My original problem was engine light on; limited performance notice when vehicle exceeded 60mph, and ASB on when engine got hot from travel.

Having said all of this, the vehicle runs smoothly, no indication of temp increase, shifts smoothly, no engine issues. You would never know I have an issue except for the dash warning light. Have driven 1200 local only miles under 55mph since these symptoms started. I put 3,000 miles a year on her.

Any suggestions?

I had the 171 code, it was a vacuum leak and MAF sensor. the leak was fixed and new sensor installed. no problems now

The P0171 is pretty common and no cause for alarm. I wouldn't be worried about breaking the bank yet. Your ABS module is having problems though. It's most likely a dry solder joint at the power post. I did this fix on my XJ8. There is info in the achives if you search on "ABS fault solder joint" or something like that. It does take some work, but a lot cheaper than paying to replace the ABS module. Oh yeah, get an OBDII code reader to reset that P0171 and see if it comes back.

Do you think I have harmed the engine by driving it under 50 mph locally? Thanks for your help. I'll check the for a vacuum leak as well.

People have driven a lot further and a lot faster with worse problems.